Question 1

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.

Accepted Answer

A)  35 m/s
B)  9.8 m/s
C)  20 m/s
D)  4.9 m/s
E)  70 m/s A

Question 2

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

Accepted Answer

A)  28 m/s.
B)  20 m/s.
C)  40 m/s.
D)  37 m/s. A

Question 3

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

Accepted Answer

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

Question 4

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?

Accepted Answer

A)  22 m
B)  43 m
C)  77 m
D)  91 m

Question 5

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.

Accepted Answer

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

Question 6

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

Accepted Answer

A)  25 m/s2.
B)  18 m/s2.
C)  9.8 m/s2.
D)  8.5 m/s2.
E)  0 m/s2.

Question 7

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.

Accepted Answer

A)  48.2 m/s
B)  28.7 m/s
C)  28.0 m/s
D)  26.3 m/s
E)  6.26 m/s

Question 8

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

Accepted Answer

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

Question 9

As shown in the figure,a projectile is fired at time t = 0.00 s,from point 0 at the upper edge of a cliff,with initial velocity components of 
And 
The projectile rises and then falls into the sea at point P.The time of flight of the projectile is 
And air resistance is negligible.At this location,g = 9.80 m/s2.What is the horizontal distance D?

Accepted Answer

A)  2,250 m
B)  2,520 m
C)  2,790 m
D)  3,060 m
E)  3,330 m

Question 10

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?

Accepted Answer

A)  6.1 m/s
B)  7.4 m/s
C)  8.1 m/s
D)  8.9 m/s

Question 11

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?

Accepted Answer

A)  100 m
B)  160 m
C)  180 m
D)  320 m

Question 12

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?

Accepted Answer

A)  0.73 m
B)  1.6 m
C)  2.7 m
D)  3.8 m
E)  7.5 m

Question 13

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?

Accepted Answer

A)  80 m/s2
B)  40 m/s2
C)  9.8 m/s2
D)  0 m/s2
E)  69 m/s2

Question 14

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.

Accepted Answer

A)  1/6 as far as on Earth
B)  36 times as far as on Earth
C)  the same distance as on Earth
D)  6 times as far as on Earth
E)    as far as on Earth

Question 15

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?

Accepted Answer

A)  10 m/s
B)  17 m/s
C)  20 m/s
D)  zero

Question 16

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

Accepted Answer

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

Question 17

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?

Accepted Answer

A)  5.00 seconds
B)  10.0 seconds
C)  15.0 seconds
D)  20.0 seconds

Question 18

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?

Accepted Answer

A)  150 m/s
B)  36 m/s
C)  130 m/s
D)  75 m/s
E)  38 m/s

Question 19

Mary and Debra stand on a snow-covered roof.They both throw snowballs with the same initial speed,but in different directions.Mary throws her snowball downward,at 30° below the horizontal;Debra throws her snowball upward,at 30° above the horizontal.Which of the following statements are true about just before the snowballs reach the ground below? (There could be more than one correct choice. )

Accepted Answer

A)  Debra's snowball will stay in the air longer than Mary's snowball.
B)  Mary's snowball will stay in the air longer than Debra's snowball.
C)  Both snowballs will take the same amount of time to hit the ground.
D)  Debra's snowball has exactly the same acceleration as Mary's snowball.
E)  Mary's snowball has a greater downward acceleration than Debra's snowball.

Question 20

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?

Accepted Answer

A)  14 m
B)  16 m
C)  20 m
D)  24 m

Exam 4: Two-Dimensional Kinematics