A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with a velocity of 80 m/s. The height of the tower is (g = 10 ) [2020]

Question

A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with a velocity of 80 m/s. The height of the tower is (g = 10 $m / s^{2}$ ) [2020]

Smart Achievers · Accepted Answer

(4)

Here, $u = 20 m/s, v = 80 m/s, g = 10 {m/s}^{2}, h = ?$

$v^{2} = u^{2} + 2 g h \Rightarrow 80^{2} = 20^{2} + 2 \times 10 \times h .$ Hence, $h = 300 m$

Solution

Q.
A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with a velocity of 80 m/s. The height of the tower is (g = 10 $m / s^{2}$ ) [2020]

1 360 m

2 340 m

3 320 m

4 300 m

Ans.
(4)

Here, $u = 20 m/s, v = 80 m/s, g = 10 {m/s}^{2}, h = ?$

$v^{2} = u^{2} + 2 g h \Rightarrow 80^{2} = 20^{2} + 2 \times 10 \times h .$ Hence, $h = 300 m$

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