Gravitational fields

Question 1

Why do astronauts in orbital space feel a sense of weightlessness

Answer 1

The astronaut and space shuttle travel at the same orbital speed

There is no normal reaction between vehicle and astronaut

Question 2

Explain how to rotation of the earth affects the reading on the bathroom scale?

Answer 2

• apparent weight would decrease
• some gravitational force provides the necessary centripetal force

Question 3

Why is potential energy negative?

Answer 3

There is zero potential at infinity

Work is done to move to infinity from a point, so potential energy falls as an object moves closer to infinity

Question 4

What is the effect on the values of Ep and V if mass is double

Answer 4

GPE would double
V - unchanged

Question 5

Why do some objects not have a circular orbit

Answer 5

The resultant force is not centripetally directed to the centre of the object they’re orbiting