Question

following figure is the speed time graph for a rocket from the moment when the fuel starts to burn, i.e., at time t=0​

Answer 1

Answer:

As the fuel of rocket burns, it ejects hot gases downwards

a) State Newton‟s third law of motion.

Answer : ‘For every action there is an equal and opposite reaction

b) Explain how Newton‟s third law of motion applies to the upward force on the

rocket and to the force on the hot gases.

downward force on hot gases – action

upward force on rocket – reaction

c) Find the force acting on the rocket and acceleration of the rocket between t=60s

and t=80s presuming that its mass remains unchanged during this interval and

is 1.6×107 kg.

a = v-u / t

= 1000 – 800 / 20

= 200/20

=10 m/s

F = m * a

= 1.6 * 107 * 10

= 1.6 * 108 Newton

d) The total weight of the rocket at t = 80s is 1.6×107 kg. Calculate the upward

force on the rocket at this time, caused by the burning fuel.