A boy standing at the top of a tower of 20 m height drops a stone. Assuming g = 10 ms-2, the velocity with which it hits the ground is

Question

A boy standing at the top of a tower of 20 m height drops a stone. Assuming g = 10 ms-2, the velocity with which it hits the ground is (A) 10.0 m/s (B) 20.0 m/s (C) 40.0 m/s (D) 5.0 m/s

Tardigrade Admin · Accepted Answer

Here, u=0, g=10 m s -2, h=20 m Let v be the velocity with which the stone hits the ground. ∴ v2=u2+2 g h or v=√2 g h =√2 × 10 × 20=20 m / s (∵ u=0)

Q. A boy standing at the top of a tower of $20 m$ height drops a stone. Assuming $g = 10 m s^{- 2},$ the velocity with which it hits the ground is

$10.0 m / s$

$20.0 m / s$

$40.0 m / s$

$5.0 m / s$

Here, $u = 0, g = 10 m s^{- 2}, h = 20 m$
Let $v$ be the velocity with which the stone hits the ground.
$∴ v^{2} = u^{2} + 2 g h$
or $v = 2 g h$
$= 2 \times 10 \times 20 = 20 m / s (∵ u = 0)$

Q. A boy standing at the top of a tower of 20m height drops a stone. Assuming g=10ms−2, the velocity with which it hits the ground is

10.0m/s

20.0m/s

40.0m/s

5.0m/s