A disc of mass 1.0 kg kept floating horizontally in air by firing bullets of mass 0.05 kg each vertically at it, at the rate of 10 per second. If the bullets rebound with the same speed, the speed with which these are fired will be-

Question

A disc of mass 1.0 kg kept floating horizontally in air by firing bullets of mass 0.05 kg each vertically at it, at the rate of 10 per second. If the bullets rebound with the same speed, the speed with which these are fired will be- (A) 0·098 m/s (B) 0·98 m/s (C) 9·8 m/s (D) 98·0 m/s

Tardigrade Admin · Accepted Answer

F=(Δ p/Δ t)=M g ⇒ 2 m n v=M g ⇒ v=(1 × 9.8/2(0.05)(10)) =9.8 m / s

Q. A disc of mass $1.0 k g$ kept floating horizontally in air by firing bullets of mass $0.05 k g$ each vertically at it, at the rate of $10$ per second. If the bullets rebound with the same speed, the speed with which these are fired will be-

0·098 m/s

0·98 m/s

9·8 m/s

98·0 m/s

$F = \frac{Δ p}{Δ t} = M g$
$\Rightarrow 2 mn v = M g$
$\Rightarrow v = \frac{1 \times 9.8}{2 ( 0.05 ) ( 10 )}$
$= 9.8 m / s$

Q. A disc of mass 1.0kg kept floating horizontally in air by firing bullets of mass 0.05kg each vertically at it, at the rate of 10 per second. If the bullets rebound with the same speed, the speed with which these are fired will be-