A ball is tossed from an upper-story window of a building. The ball is given an

Question

A ball is tossed from an upper-story window of a building. The ball is given an initial velocity of 8.10 m/s at an angle of 15.0° below the horizontal. It strikes the ground 5.00 s later.
(a) How far horizontally from the base of the building does the ball strike the ground?

How many m?

(b) Find the height from which the ball was thrown.
How many m?

(c) How long does it take the ball to reach a point 10.0 m below the level of launching?
How many s?

Explanation / Answer

(a) How far horizontally from the base of the building does the ball strike the ground? x = v cos@ * t = 8.10 * cos15 * 5.00 = 39.11 m (b) Find the height from which the ball was thrown. y = vi t + 0.5 gt^2 h = v cos@ * t + 0.5 g t^2 = 39.11 + 0.5 * 9.8 * 5^2 = 161.61 m (c) How long does it take the ball to reach a point 10.0 m below the level of launching? h = v cos@ * t + 0.5 g t^2 10 = 8.10 * cos15 * t + 0.5 * 9.8 * t^2 ==> 4.9t^2 + 7.823t - 10 = 0 Solving this we get t = 0.8382 s

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