A ball is thrown vertically upwards with a velocity of 20m/s from the

1.	A ball is thrown vertically upwards with a velocity of 20m/s from the top of a building
Answer» H = u²/(2g)H = 20²/(2×10)H = 20 mThe ball will reach 20 m high from the point of projection.It reaches 20 + 20.5 = 40.5m high from the ground.(b)t1 = 2u/gt1 = 2×20/10t1 = 4 secondsIf v is the velocity with which it hits the ground then,v = √(u² + 2aS)v = √(20² + 2×10×25)v = 30 m/sv = u + att2 = (v - u)/gt2 = (30 - 20)/10t2 = 1 secondTime taken for it to hit the ground = t1 + t2= 4 + 1= 5 secondsNote: I took g = 10m/s².

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