A student is riding in the back of a truck traveling along a straight level road
ID: 1962964 • Letter: A
Question
A student is riding in the back of a truck traveling along a straight level road at Vt=20m/s. He faces toward the rear of the truck and throws a ball with a velocity of 15m/s at an angle of 37 degrees above the horizontal relative to the truck. He releases the ball 2.0m above the ground level. Ignore air resistance. use tan 37 =3/4; g=10m/s^2.How many seconds are required for the ball to strike the road?
The observer is at ground level (horizontal).
The velocity of the ball projected as seen by the observer is 12m/s.
The horizontal velocity relative to the observer is 8m/s
The vertical velocity of the ball is 9 m/s
Explanation / Answer
Using the previous answer (see other post) for the time in the air (total of 2.04 seconds) we know that the ball will travel a horizontal distance of distance = horiz speed * time = 8 m/s * 2.04 s = 16.32 meters So the guy throwing the ball should release it when he is a horizontal distance of 16.32 m past the observer. The ball will then travel 16.32 m (in the direction opposite the direction the truck is moving) and hit the ground level with the observer. NOTE: double check what value of g you are supposed to use. I used 9.8, but if you are supposed to use 10 my numbers will be a little off (the answer to this question and the total time).
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