2-D Kinematics Homework SheetConceptual Physics
1.A plane flying horizontally above Earth’s surfaceat 125 m/s drops a crate. Thecrate strikes the ground 10.0 seconds later. How far horizontally will the crate move before it hits the ground?
(1) 125 m (2) 98 m (3) 1250 m (3) 490 m
2.A child walks 5.0 meters north, then 4.0 meterseast, and finally 2.0 meters south. What is themagnitude of the resultant displacement of thechild after the entire walk?
(1) 1.0 m (2) 5.0 m (3) 3.0 m (4) 11.0 m
3. What is the velocity of a projectile at the top of its trajectory? What is the acceleration of a projectile as it moves through the air?
4.A golf ball is hit at an angle of 45° above thehorizontal. What is the acceleration of the golfball at the highest point in its trajectory?[Neglect friction.]
(1) 9.8 m/s2 upward (2) 9.8 m/s2 downward (3) 6.9 m/s2 horizontal (4) 0.0 m/s2
5.A ball is thrown horizontally at a speed of10 meters per second from the top of a cliff. Ifthe ball hits the ground 3.0 seconds later,approximately how high is the cliff?
(1) 3.0 m (2) 30 m (3) 44 m (4) 96 m
6.A stream is 30 meters wide and itscurrent flows southward at 1.5 meters persecond. A toy boat is launched with avelocity of 2.0 meters per second eastwardfrom the west bank of the stream.
a. What is the magnitude of the boat’s resultantvelocity as it crosses the stream?
(1) 0.5 m/s (2) 2.5 m/s (3) 3.0 m/s (4) 3.5 m/s
b. How much time is required for the boat to reachthe opposite bank of the stream?
(1) 8.6 s (2) 12 s (3) 15 s (4) 60. s
7. A penguin slides off an iceberg that is 2.5m high. It lands in the water 5.5m from the iceberg.
a.How does the penguin’s trajectory (pathway) differ from the penguin’s displacement?
(include a diagram)
b. Draw a scaled vector diagram of the penguin’s displacement. (let 1m = 1cm on your diagram)
- Draw and label the resultant displacement.
d.Determine the magnitude and direction of the displacement. (6.04 m, below horizontal)
8.A projectile is launched into the air with an initial speed of vi at a launch angle of 30°above the horizontal. The projectile lands on the ground 2.0 seconds later.
a. On the diagram below, sketch the ideal path of the projectile. [1]
b. How does the time up to the maximum height compare to the time it takes to come back down?
c. How does the total horizontal distance traveled by the projectile change as the launch angle
is increasedfrom 30° to 45° above the horizontal? [Assume the same initial speed, vi.] [1]
Answers to front:
1. 3, 2.2 3.vx = vx, vy = 0 m/s, a = 9.8 m/s2 downward, 4. 2, 5. 3, 6a. 2, 6b. 3, 7. the trajectory is parabolic in shape, the displacement is the resultant (hypotenuse) of the dx and dy. 8a. parabolic in shape, b. the same, c. range increases. It will go the farthest at 45o. The range will decrease as the launch angle is increased from 45o to 90o. Complementary angles produce the same range.
9. In the following problem, draw a diagram and identify the given quantities in the tables below.
A fearless clavadista (cliff diver) dives horizontally from the top of 43 m cliff in Acapulco. He has to dive with a high enough horizontal velocity to clear the jagged rocks below, which jut out just about 9 m from the base of the cliff. Muy Macho!
How long will it take for the diver to reach the water? (2.96 s)
What is the diver’s minimum initial velocity needed to clear the cliffs? (3.04 m/s)
y x
viy = 0 m/svx =
dy =dx =
ty =tx =
ay = 9.8 m/s2