Question

A stone thrown upward with a speed u from the top
of the tower reaches the ground with a velocity 3u.
The Reight of he tower is
​

Answer 1

Answer:

Height of the tower is 2u²/5 metres.

Explanation:

Let the height of the tower be h metres.

When we throw the ball upward from height h at velocity u, it will reach the same point with the same velocity but in the opposite direction.

Now we apply the 3rd equation in the motion for the rest of the motion.

v² = u² + 2as

⇒ (3u)² = u² + 2*10*h

⇒ 9u² = u² + 20h

⇒ 8u² = 20h

⇒2u²/5 = h

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