PHY CH 3 Flashcards

If a vector pointing upward has a positive magnitude, a vector pointing downward has a negative magnitude.

1. A) True
2. B) False

Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum

1. A) is equal to 2.0 m.
2. B) could be as small as 2.0 m or as large as 12 m.
3. C) is equal to 12 m.
4. D) is equal to 8.6 m.

Two vectors, of magnitudes 20 mm and 50 mm, are added together. Which one of the following is a possible value for the magnitude of the resultant?

1. A) 10 mm
2. B) 20 mm
3. C) 40 mm
4. D) 80 mm

The magnitude of the resultant of two vectors cannot be less than the magnitude of either of those two vectors.

1. A) True
2. B) False

If + = and their magnitudes are given by A + B = C, then the vectors and are oriented

1. A) perpendicular relative to one other.
2. B) parallel to each other (in the same direction).
3. C) antiparallel to each other (in opposite directions).
4. D) It is impossible to know from the given information.

If - = 0, then the vectors and have equal magnitudes and are directed in the same direction.

1. A) True
2. B) False

If three vectors add to zero, they must all have equal magnitudes.

1. A) True
2. B) False

The sum of two vectors of fixed magnitudes has the greatest magnitude when the angle between these two vectors is

1. A) 90°
2. B) 180°
3. C) 60°
4. D) 0°
5. E) 270°

The sum of two vectors of fixed magnitudes has its minimum magnitude when the angle between these vectors is

1. A) 0°
2. B) 90°
3. C) 270°
4. D) 180°
5. E) 360°

Vectors and obey the equation + = 0. These vectors satisfy which one of the following statements?

1. A) Vectors and are at right angles to each other.
2. B) Vectors and point in the same direction.
3. C) Vectors and have the same magnitudes.
4. D) The magnitude of is the negative of the magnitude of .

If a vector's components are all negative, then the magnitude of the vector is negative.

1. A) True
2. B) False

The magnitude of a vector can never be less than the magnitude of any of its components.

1. A) True
2. B) False

The magnitude of a vector an only zero if all of its components are zero.

1. A) True
2. B) False

If a vector has components Ax < 0, and Ay > 0, then the angle that this vector makes with the positive x-axis must be in the range

1. A) 0° to 90°
2. B) 90° to 180°
3. C) 180° to 270°
4. D) 270° to 360°

If a vector has components Ax < 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range

1. A) 0° to 90°
2. B) 90° to 180°
3. C) 180° to 270°
4. D) 270° to 360°

If a vector has components Ax > 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range

1. A) 0° to 90°
2. B) 90° to 180°
3. C) 180° to 270°
4. D) 270° to 360°
5. E) cannot be determined without additional information

The eastward component of vector is equal to the westward component of vector and their northward components are equal. Which one of the following statements must be correct for these two vectors?

1. A) Vector is parallel to vector .
2. B) Vector is antiparallel (in the opposite direction) to vector .
3. C) Vector must be perpendicular to vector .
4. D) The magnitude of vector must be equal to the magnitude of vector .
5. E) The angle between vector and vector must be 90°.

Vector A is along the +x-axis and vector B is along the +y-axis. Which one of the following statements is correct with respect to these vectors?

1. A) The x component of vector is equal to the x component of vector .
2. B) The y component of vector is equal to the y component of vector .
3. C) The x component of vector is equal to the y component of vector .
4. D) The y component of vector is equal to the x component of vector .

A boulder rolls off of a very high cliff and experiences no significant air resistance. While it is falling, its trajectory is never truly vertical.

1. A) True
2. B) False

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity

1. A) remains zero.
2. B) remains a non-zero constant.
3. C) continuously increases.
4. D) continuously decreases.
5. E) first decreases and then increases.

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration

1. A) is always zero.
2. B) remains a non-zero constant.
3. C) continuously increases.
4. D) continuously decreases.
5. E) first decreases and then increases

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration

1. A) is always zero.
2. B) remains a non-zero constant.
3. C) continuously increases.
4. D) continuously decreases.
5. E) first decreases and then increases.

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.)

1. A) The speed of the object is constant but its velocity is not constant.
2. B) The acceleration of the object is +g when the object is rising and -g when it is falling.
3. C) The acceleration of the object is zero at its highest point.
4. D) The speed of the object is zero at its highest point.
5. E) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?

1. A) It is impossible to tell because we do not know their masses.
2. B) the stone
3. C) the ball
4. D) Both are traveling at the same speed.

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles.

1. A) The thrown pebble hits first.
2. B) The dropped pebble hits first.
3. C) They hit at the same time.
4. D) We cannot tell without knowing which pebble is heavier.

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

1. A) be behind the package.
2. B) be directly over the package.
3. C) be in front of the package.
4. D) depend on the speed of the plane when the package was released.

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below

1. A) the splashdown speed of James is larger than that of John.
2. B) the splashdown speed of John is larger than that of James.
3. C) they will both have the same splashdown speed.
4. D) the splashdown speed of James must be 9.8 m/s larger than that of John.
5. E) the splashdown speed of John must be 25 m/s larger than that of James.

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance.

1. A) James reaches the surface of the lake first.
2. B) John reaches the surface of the lake first.
3. C) James and John will reach the surface of the lake at the same time.
4. D) Cannot be determined without knowing the mass of both James and John.
5. E) Cannot be determined without knowing the weight of both James and John.

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory

1. A) both the velocity and the acceleration of the soccer ball are zero.
2. B) neither the ball's velocity nor its acceleration are zero.
3. C) the ball's acceleration is zero but its velocity is not zero.
4. D) the ball's acceleration points upward.
5. E) the ball's velocity points downward.

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground? (There could be more than one correct choice.)

1. A) Its horizontal velocity component is zero.
2. B) Its velocity is vertical.
3. C) Its vertical velocity component is the same as it was just as it was launched.
4. D) Its horizontal velocity component is the same as it was just as it was launched.
5. E) Its speed is the same as it was just as it was launched.

If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?

1. A) in the forward direction
2. B) in the backward direction
3. C) outward away from the earth
4. D) inward toward the earth
5. E) The acceleration is zero because the speed is constant.

An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.

1. A) Both vectors point in the same direction.
2. B) The vectors point in opposite directions.
3. C) The vectors are perpendicular to each other.
4. D) The acceleration is zero but the velocity is constant

The Moon is accelerated toward the earth, so it is gradually getting closer to the earth.

1. A) True
2. B) False
3. C) The moon is not accelerated toward the earth.

You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat

1. A) directly toward the west.
2. B) directly toward the north.
3. C) in a general southwesterly direction.
4. D) in a general northwesterly direction.

The x component of vector A is 8.7 units, and its y component is -6.5 units. The magnitude of A is closest to

1. A) 9.9 units
2. B) 7.9 units
3. C) 8.9 units
4. D) 11 units
5. E) 12 units

When rolled down a mountainside at 7.0 m/s, the horizontal component of its velocity vector was 1.8 m/s. What was the angle of the mountain surface above the horizontal?

1. A) 75°
2. B) 57 °
3. C) 33°
4. D) 15°

When Jeff ran up a hill at 7.0 m/s, the horizontal component of his velocity vector was 5.1 m/s. What was the vertical component of Jeff's velocity?

1. A) 4.8 m/s
2. B) 4.3 m/s
3. C) 3.8 m/s
4. D) 3.4 m/s

The x component of vector A is 5.3 units, and its y component is -2.3 units. The angle that vector A makes with the +x-axis is closest to

1. A) 340°
2. B) 160°
3. C) 250°
4. D) 110°
5. E) 23°

A player throws a football 50.0 m at 61.0° north of west. What is the westward component of the displacement of the football?

1. A) 64.7m
2. B) 55.0 m
3. C) 0.00 m
4. D) 74.0 m
5. E) 24.2 m

A boy jumps with a velocity of magnitude 20.0 m/s at an angle of 25.0° above the horizontal. What is the horizontal component of the boy's velocity?

1. A) 18.1 m/s
2. B) 15.6 m/s
3. C) 8.45 m/s
4. D) 12.6 m/s
5. E) 9.33 m/s

The magnitude of A is 5.5 m, and this vector lies in the second quadrant and makes an angle of 34 ° with the +y-axis. The components of A are closest to:

1. A) = -3.1 m, = 4.6 m.
2. B) = 3.1 m, = -4.6 m.
3. C) = 4.6 m, = -3.1 m.
4. D) = -4.6 m, = 3.1 m.
5. E) = -4.6 m, = -3.1 m.

A car travels 20 km west and then 20 km south. What is the magnitude of its displacement vector?

1. A) 0 km
2. B) 20 km
3. C) 28 km
4. D) 40 km

You walk to the north, then turn 60° to your right and walk another How far are you from where you originally started?

1. A) 68 m
2. B) 39 m
3. C) 75 m
4. D) 35 m

You walk 53 m to the north, then you turn 60° to your right and walk another Determine the direction of your displacement vector. Express your answer as an angle relative to east.

1. A) 63° N of E
2. B) 50° N of E
3. C) 57° N of E
4. D) 69° N of E

If vector A has components Ax = -3.0 lb and Ay = -4.0 lb, and vector has components Bx = 3.0 lb and By = -8.0 lb, what is the magnitude of vector C = A - B?

1. A) 13 lb
2. B) 16 lb
3. C) 140 lb
4. D) 7.2 lb

Vector A has magnitude 2 units and is directed to the north. Vector B has magnitude and is directed to the south. Calculate the magnitude and direction of A-B

1. A) 7 units, north
2. B) 7 units, south
3. C) 3 units, north
4. D) 3 units, south

Two perpendicular vectors, A and B, are added together giving vector C. If the magnitudes of both vectors and are doubled without changing their directions, the magnitude of vector C will

1. A) increase by a factor of 8.
2. B) increase by a factor of 4.
3. C) increase by a factor of 2.
4. D) increase by a factor of square root 2.
5. E) not change.

Vector M= 4.00 m points eastward and vector N= 3.00 m points southward. The resultant vector M+N is given by

1. A) 5.00 m at an angle of 36.9° south of east.
2. B) 5.00 m at an angle of 53.1° south of east.
3. C) 5.00 m at an angle of 71.6° south of east.
4. D) 5.00 m at an angle of 18.4° south of east.
5. E) 5.00 m at an angle of 26.6° south of east.

Vector A has a magnitude of 6.0 m and points 30° north of east. Vector B has a magnitude of 4.0 m and points 30° east of north. The resultant vector A+B is given by

1. A) 0.70 m at an angle of 42° north of east.
2. B) 14 m at an angle of 42° north of east.
3. C) 1.1 m at an angle of 42° north of east.
4. D) 9.7 m at an angle of 42° north of east.
5. E) 2.0 m at an angle of 42° north of east.

Vector A has a magnitude of 6.0 m and points 30° north of east. Vector B has a magnitude of 4.0 m and points 30° west of north. The resultant vector A+ B is given by

1. A) 9.8 m at an angle of 64° east of north.
2. B) 9.8 m at an angle of 26° north of east.
3. C) 7.2 m at an angle of 26° east of north.
4. D) 3.3 m at an angle of 26° north of east.
5. E) 3.3 m at an angle of 64° east of north.

Vector A has a magnitude of 6.0 m and points 30° north of east. Vector B has a magnitude of 4.0 m and points 30° west of south. The resultant vector A+B is given by

1. A) 2.7 m at an angle of 8.3° south of east.
2. B) 2.7 m at an angle of 8.3° east of south.
3. C) 3.2 m at an angle of 8.3° east of south.
4. D) 3.2 m at an angle of 8.3° south of east.
5. E) 2.3 m at an angle of 8.3° south of east.

Vector A has a magnitude of 6.0 m and points 30° south of east. Vector B has a magnitude of 4.0 m and points 30° west of south. The resultant vector A+B is given by

1. A) 7.2 m at an angle of 64° south of east.
2. B) 3.3 m at an angle of 64° south of east.
3. C) 9.8 m at an angle of 26° south of east.
4. D) 9.8 m at an angle of 64° south of east.
5. E) 3.3 m at an angle of 26° south of east.

An airplane undergoes the following displacements, all at the same altitude: First, it flies in a direction 30.0° east of north. Next, it flies due south. Finally, it flies 30.0° north of west. Use components to determine how far the airplane ends up from its starting point.

1. A) 71.5 km
2. B) 73.0 km
3. C) 74.4 km
4. D) 70.1 km
5. E) 68.7 km

Three forces, 1, 2, and 3, each of magnitude 70 N, all act on an object as shown in the figure. The magnitude of the resultant force acting on the object is

1. A) 35 N.
2. B) 70 N.
3. C) 140 N.
4. D) 210 N.
5. E) 0 N.

The figure shows four vectors, A, B, C, and d, having magnitudes 12.0 m, 10.0 m, 8.0 m, and 4.0 m, respectively. The sum of these four vectors is

1. A) 16.4 m at an angle 77.8° with respect to +x-axis.
2. B) 16.4 m at an angle 12.3° with respect to +x-axis.
3. C) 19.5 m at an angle 77.8° with respect to +x-axis.
4. D) 19.5 m at an angle 12.3° with respect to +x-axis.
5. E) 8.20 m at an angle 77.8° with respect to +x-axis.

A ball is thrown with an initial velocity of 20 m/s at an angle of 60° above the horizontal. If we can neglect air resistance, what is the horizontal component of its instantaneous velocity at the exact top of its trajectory?

1. A) 10 m/s
2. B) 17 m/s
3. C) 20 m/s
4. D) zero

A ball is thrown at an original speed of 8.0 m/s at an angle of 35° above the horizontal. If there is no air resistance, what is the speed of the ball when it returns to the same horizontal level?

1. A) 4.0 m/s
2. B) 8.0 m/s
3. C) 16 m/s
4. D) 9.8 m/s

A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. A stopwatch measures the stone's trajectory time from the top of the cliff to the bottom to be 4.3 s. What is the height of the cliff if air resistance is negligibly small?

1. A) 22 m
2. B) 43 m
3. C) 77 m
4. D) 91 m

A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water, assuming negligible air resistance?

1. A) 14 m
2. B) 16 m
3. C) 20 m
4. D) 24 m

A ball thrown horizontally from a point 24 m above the ground, strikes the ground after traveling horizontally a distance of 18 m. With what speed was it thrown, assuming negligible air resistance?

1. A) 6.1 m/s
2. B) 7.4 m/s
3. C) 8.1 m/s
4. D) 8.9 m/s

The acceleration due to gravity on the Moon is only one-sixth of that on Earth, and the Moon has no atmosphere. If you hit a baseball on the Moon with the same effort (and therefore at the speed and angle) as on Earth, how far would the ball would travel on the Moon compared to on Earth? Neglect air resistance on Earth.

1. A) 1/6 as far as on Earth
2. B) 36 times as far as on Earth
3. C) the same distance as on Earth
4. D) 6 times as far as on Earth
5. E) as far as on Earth

A boy throws a rock with an initial velocity of at 30.0° above the horizontal. How long does it take for the rock to reach the maximum height of its trajectory if air resistance is negligibly small and g = 9.80 m/s2?

1. A) 0.160 s
2. B) 0.282 s
3. C) 0.313 s
4. D) 0.441 s

A cat leaps to try to catch a bird. If the cat's jump was at 60° off the ground and its initial velocity was what is the highest point of its trajectory, neglecting air resistance?

1. A) 0.29 m
2. B) 0.58 m
3. C) 10.96 m
4. D) 0.19 m

A fisherman casts his bait toward the river at an angle of 25° above the horizontal. As the line unravels, he notices that the bait and hook reach a maximum height of What was the initial velocity he launched the bait with? Assume that the line exerts no appreciable drag force on the bait and hook and that air resistance is negligible.

1. A) 18 m/s
2. B) 7.9 m/s
3. C) 7.6 m/s
4. D) 6.3 m/s

A football kicker is attempting a field goal from out. The ball is kicked and just clears the lower bar with a time of flight of If the angle of the kick was 45°, what was the initial speed of the ball, assuming no air resistance?

1. A) 21.5 m/s
2. B) 19.7 m/s
3. C) 2.2 m/s
4. D) 39 m/s

You throw a rock horizontally off a cliff with a speed of 20 m/s and no significant air resistance. After 2.0 s, the magnitude of the velocity of the rock is closest to

1. A) 28 m/s
2. B) 20 m/s
3. C) 40 m/s
4. D) 37 m/s

A hockey puck slides off the edge of a platform with an initial velocity of 20 m/s horizontally. The height of the platform above the ground is 2.0 m. What is the magnitude of the velocity of the puck just before it touches the ground? You can neglect air resistance.

1. A) 21 m/s
2. B) 22 m/s
3. C) 24 m/s
4. D) 25 m/s
5. E) 6.3 m/s

A hockey puck slides off the edge of a horizontal platform with an initial velocity of 20 m/s horizontally and experiences no significant air resistance. The height of the platform above the ground is 2.0 m. What is the magnitude of the vertical component of the velocity of the puck just before it hits the ground?

1. A) 20 m/s
2. B) 6.3 m/s
3. C) 13 m/s
4. D) 15 m/s
5. E) 21 m/s

A hockey puck slides off the edge of a horizontal platform with an initial velocity of 28.0 m/shorizontally in a city where the acceleration due to gravity is 9.81 m/s2. The puck experiences no significant air resistance as it falls. The height of the platform above the ground is 2.00 m. What is the angle below the horizontal of the velocity of the puck just before it hits the ground?

1. A) 77.2°
2. B) 72.6°
3. C) 12.8°
4. D) 12.6°
5. E) 31.8°

A plane flying horizontally at a speed of 50 m/s and at an elevation of 160 m drops a package, and 2.0 s later it drops a second package. How far apart will the two packages land on the ground if air resistance is negligible?

1. A) 100 m
2. B) 160 m
3. C) 180 m
4. D) 320 m

In a room where g = 9.81 m/s2, a hockey puck slides off the edge of a platform with an initial velocity of 28.0 m/s horizontally. The height of the platform above the ground is 2.00 m. What is the speed of the puck just before it hits the ground? The air resistance is negligibly small.

1. A) 48.2 m/s
2. B) 28.7 m/s
3. C) 28.0 m/s
4. D) 26.3 m/s
5. E) 6.26 m/s

A ball rolls over the edge of a platform with only a horizontal velocity. The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m. What is the horizontal velocity of the ball just before it touches the ground? Neglect air resistance.

1. A) 35 m/s
2. B) 9.8 m/s
3. C) 20 m/s
4. D) 4.9 m/s
5. E) 70 m/s

A person throws a ball horizontally from the top of a building that is 24.0 m above the ground level. The ball lands 100 m down range from the base of the building. What was the initial velocity of the ball? Neglect air resistance and use g = 9.81 m/s2.

1. A) 202 m/s
2. B) 9.80 m/s
3. C) 19.6 m/s
4. D) 45.2 m/s
5. E) 94.4°

A wind farm generator uses a two-bladed propeller mounted on a pylon at a height of 20 m, as shown in the figure. The width of the pylon is very narrow, and the length of each propeller blade is 12 m. A tip of the propeller breaks off just when the propeller is vertical. The fragment flies off horizontally, falls, and strikes the ground at point P with negligible air resistance. Just before the fragment broke off, the propeller was turning uniformly, taking 1.2 s for each rotation. How far is point P from the base of the pylon?

1. A) 120 m
2. B) 130 m
3. C) 140 m
4. D) 150 m
5. E) 160 m

A boy throws a ball with an initial velocity of 25 m/s at an angle of 30° above the horizontal. If air resistance is negligible, how high above the projection point is the ball after 2.0 s?

1. A) 5.4 m
2. B) 13 m
3. C) 25 m
4. D) 43 m
5. E) 50 m

A projectile is fired from ground level with a speed of 150 m/s at an angle 30° above the horizontal on an airless planet where g = 10.0 m/s2. What is the horizontal component of its velocity after 4.0 s?

1. A) 150 m/s
2. B) 35 m/s
3. C) 130 m/s
4. D) 75 m/s
5. E) 38 m/s

A high-speed dart is shot from ground level with a speed of 150 m/s at an angle 30° above the horizontal. What is the vertical component of its velocity after 4.0 s if air resistance is neglected?

1. A) 150 m/s
2. B) 36 m/s
3. C) 130 m/s
4. D) 75 m/s
5. E) 38 m/s

A child is trying to throw a ball over a fence. She gives the ball an initial speed of 8.0 m/s at an angle of 40° above the horizontal. The ball leaves her hand 1.0 m above the ground and the fence is 2.0 m high. The ball just clears the fence while still traveling upwards and experiences no significant air resistance. How far is the child from the fence?

1. A) 0.73 m
2. B) 1.6 m
3. C) 2.7 m
4. D) 3.8 m
5. E) 7.5 m

A boy kicks a football from ground level with an initial velocity of 20 m/s at an angle of 30° above the horizontal. What is the horizontal distance to the point where the football hits the ground if we neglect air resistance?

1. A) 20 m
2. B) 35 m
3. C) 18 m
4. D) 60 m
5. E) 30.0 m

An athlete competing in the long jump leaves the ground with a speed of 9.14 m/s at an angle of 55° with the vertical. What is the length of the athlete's jump if air resistance is of no significance?

1. A) 0.88 m
2. B) 8.0 m
3. C) 12 m
4. D) 17 m
5. E) 4.0 m

An athlete competing in the long jump leaves the ground with a speed of 9.14 m/s at an angle of 35° above the horizontal. How long does the athlete stay in the air, assuming no significant air resistance?

1. A) 0.50 s
2. B) 0.88 s
3. C) 1.1 s
4. D) 2.5 s
5. E) 0.54 s

An athlete participates in an interplanetary discus throw competition during an Olympiad that takes place on a planet where the acceleration due to gravity is 9.7 m/s2. He throws the discus with an initial velocity of 20 m/s at an angle of 60° from the vertical. Neglecting air resistance and the height of the discus at the point of release, what is the range of the discus?

1. A) 21 m
2. B) 60 m
3. C) 36 m
4. D) 40 m
5. E) 32 m

A child throws a ball with an initial speed of 8.0 m/s at an angle of 40° above the horizontal. The ball leaves her hand 1.0 m above the ground. At what angle below the horizontal does the ball approach the ground?

1. A) 35°
2. B) 42°
3. C) 48°
4. D) 40°
5. E) 65°

The horizontal and vertical components of the initial velocity of a football are 16 m/s and 20 m/s respectively. If there is no air resistance, how long does it take the football to reach the top of its trajectory?

1. A) 1.0 s
2. B) 2.0 s
3. C) 3.0 s
4. D) 4.0 s
5. E) 5.0 s

A projectile is fired at an angle above the horizontal at a location where g = 9.8 m/s2. The initial x and y components of its velocity are 86.6 m/s and 50 m/s respectively. At what angle was the projectile fired above the horizontal?

1. A) 45°
2. B) 60°
3. C) 30°
4. D) 90°
5. E) 75°

A projectile is fired from ground level at an angle above the horizontal on an airless planet where g = 10.0 m/s2. The initial x and y components of its velocity are 86.6 m/s and 50.0 m/s respectively. How long after firing does it take before the projectile hits the level ground?

1. A) 5.00 seconds
2. B) 10.0 seconds
3. C) 15.0 seconds
4. D) 20.0 seconds

A projectile is launched with an initial velocity of 80 m/s at 30° above the horizontal. Neglecting air resistance, what is horizontal component of the projectile's acceleration?

1. A) 80 m/s2
2. B) 40 m/s2
3. C) 9.8 m/s2
4. D) 0 m/s2
5. E) 69 m/s2

A boy kicks a football with an initial velocity of 20 m/s at an angle of 25° above the horizontal. If we neglect air resistance, the magnitude of the acceleration of the ball while it is in flight is

1. A) 25 m/s2.
2. B) 18 m/s2.
3. C) 9.8 m/s2.
4. D) 8.5 m/s2.
5. E) 0 m/s2.