Physics 5054 · O Level · Forces

Forces — practice question

Fig. 9.1 depicts an astronaut in space close to a space station orbiting above the Earth. The astronaut plus all of his equipment has a total mass of 160 kg. At first the astronaut is stationary relative to the space station, then the rope pulls him towards the space station. His acceleration towards the space station is $0.35\,\text{m s}^{-2}$ for 1.2 s.
(a(i))[2]

Calculate the resultant force needed to make a mass of 160 kg accelerate at $0.35\,\text{m s}^{-2}$.

(a(ii))[2]

Calculate the speed of the astronaut after 1.2 s.

(b(i))[2]

The resultant force acting on the astronaut is constant for 1.2 s, but after that it drops to zero at once when the rope becomes slack. On Fig. 9.2, sketch the speed-time graph for the astronaut for the first 3.0 s of his motion.

(b(ii))[2]

Describe how the distance travelled by the astronaut in the first 3.0 s can be determined from the speed-time graph.

(c(i))[3]

A force acts on the space station to keep it in this orbit. On Fig. 9.3, draw an arrow to show the direction of this force. Explain what causes this force.

(c(ii))[2]

State what is meant by the velocity of an object.

(c(iii))[2]

State and explain what happens during the orbit to (1) the velocity of the space station, and (2) the kinetic energy of the space station.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: F = ma = 160 \times 0.35

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI