Question

5. What is the apparent weight of a 75 kg astronaut 4200 km from the centre of Earth’s

moon in a space vehicle?

a) Moving at constant velocity

b) Accelerating toward the moon at 2.9 m/s2

Answer 1

Weight: w = 75kg

Distance: d = 4200km

Part(a)

moving at constant velocity,

$g=\frac{GM_{moon}}{r^2}$

=$\frac{6.67×10^{−11}×7.35×10^{22}}{(4.2×10^6)^2}$

=$209 m/s=0.277m/s^2$

Apparent weight:

=75×0.277=20.775N

(b)

Accelerating towards the moon at

Total force:

=75×2.9=217N

Thus, apparent weight is:

=257−20.775=236.225N

Radially away from the moon.