I have no idea which equations to use and how to get the answers, (a). A basebal

Question

I have no idea which equations to use and how to get the answers,

(a). A baseball is struck 1.0 meters above the ground and given an inital velocity of 49 m/s, 30 degrees above the horizontal. If it is caught also at 1.0 meters about the ground, for how long was it in the air? ( the answer is 5.0s)

(b). A 70 kg crate starting at rest slides down a rough ramp 4.0 m long, inclined at 30 degrees above the horizontal. At the bottom, it is moving at 4.4 m/s. What was the work done by friction on the crate ( the answer is -690 J)

Explanation / Answer

Here ,

initial speed , u = 49 m/s

theta = 30 degree

as the ball is caught at the same height

time of flight = 2 * u * sin(theta)/g

time of flight = 2 * 49 * sin(30)/9.8

time of flight = 5 s

baseball is in the air for 5 s

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