Answer:
119 kgStep-by-step explanation:
Given that,
Force exerted by the rocket = 500 N
Time for which the force is exerted = 5 seconds
Speed = 21 m/s
We know that,
Impulse = Force × Time
= 500 × 5
= 2500 N per second
Also, Impulse = Mass × Velocity
So, 2500 = m × 21
Thus,
m = 2500/21= 119.05
≈ 119 kg