Bullets of mass 0.03 kg each hit a plate at the rate of 200 bullets per second with a velocity of 50 m s -1 and reflect back with a velocity of 30 m s -1. The average force (in newton) acting on the plate is

Question

Bullets of mass 0.03 kg each hit a plate at the rate of 200 bullets per second with a velocity of 50 m s -1 and reflect back with a velocity of 30 m s -1. The average force (in newton) acting on the plate is (A) 120 (B) 180 (C) 300 (D) 480

Tardigrade Admin · Accepted Answer

Change in momentum of one bullet =m(v-u)=0.03 × 50-(-30) =2.4 kg m s -1 Average force = rate of change of momentum of 200 bullets =200 × 2.4=480 N

Q. Bullets of mass $0.03 k g$ each hit a plate at the rate of $200$ bullets per second with a velocity of $50 m s^{- 1}$ and reflect back with a velocity of $30 m s^{- 1}$ . The average force (in newton) acting on the plate is

$120$

$180$

$300$

$480$

Change in momentum of one bullet
$= m (v - u) = 0.03 \times {50 - (- 30)} = 2.4 k g m s^{- 1}$
Average force $=$ rate of change of momentum of $200$ bullets
$= 200 \times 2.4 = 480 N$

Q. Bullets of mass 0.03kg each hit a plate at the rate of 200 bullets per second with a velocity of 50ms−1 and reflect back with a velocity of 30ms−1. The average force (in newton) acting on the plate is

120

180

300

480