A stone is shot straight upward with a speed of 20 m/s from a tower 200 m high. The speed with which it strikes the ground is approximately

Question

A stone is shot straight upward with a speed of 20 m/s from a tower 200 m high. The speed with which it strikes the ground is approximately (A) 60 m/s (B) 65 m/s (C) 70 m/s (D) 75 m/s

Tardigrade Admin · Accepted Answer

Speed of stone in a vertically upward direction is

20 m / s

.
So for vertical downward motion we will consider

u = - 20 m / s

v^{2} = u^{2} + 2 g h = (- 20)^{2} + 2 \times 9.8 \times 200 = 4320 m / s ∴ v ≃ 65 m / s

Q. A stone is shot straight upward with a speed of 20m/s from a tower 200m high. The speed with which it strikes the ground is approximately

60 m/s

65 m/s

70 m/s

75 m/s

Speed of stone in a vertically upward direction is 20m/s. So for vertical downward motion we will consider u=−20m/s v2=u2+2gh=(−20)2+2×9.8×200=4320m/s∴v≃65m/s​

Q. A stone is shot straight upward with a speed of $20 m / s$ from a tower $200 m$ high. The speed with which it strikes the ground is approximately

Speed of stone in a vertically upward direction is $20 m / s$ .
So for vertical downward motion we will consider $u = - 20 m / s$
$v^{2} = u^{2} + 2 g h = (- 20)^{2} + 2 \times 9.8 \times 200 = 4320 m / s ∴ v ≃ 65 m / s$