Question

In a rocket, fuel burns at a rate of 1 kg/s and is ejected with a velocity of 48 km/s. Then the force exerted by the exhaust gases on the rocket is?

a) 48 N

b) 48,000 N

c) 2 N

d) 2,000 N

Answer 1

Using the conservation of momentum and Newton's third law, the force exerted by exhaust gases on a rocket is the product of the mass flow rate and the exhaust velocity, resulting in a force of 48,000 N.

Step-by-step explanation:

The force exerted by the exhaust gases on the rocket can be calculated using Newton's third law of motion and the conservation of momentum.

The momentum change per second of the exhaust gas is equal to the mass flow rate multiplied by the expulsion velocity. This is also the force on the rocket, according to Newton's third law.

The mass flow rate of the fuel is 1 kg/s, and the exhaust velocity is 48 km/s, which is 48,000 m/s when converted to meters per second.

To find the force (F), use the following:

F = Δp/t = mass flow rate × exhaust velocity

This gives us:

F = 1 kg/s × 48,000 m/s = 48,000 N

So, the correct answer to the student's question is b) 48,000 N.