Question

Which of the following is correct statement as the moon orbits the Earth in a circular orbit,

• A. Its velocity is parallel to the gravitational force between the moon and the Earth
• B. Its speed increases
• C. Its acceleration increases
• D. Its acceleration is constant in both magnitude and direction
• E. Its acceleration is constant in magnitude but variable in direction

Answer 1

The correct option is E Its acceleration is constant in magnitude but variable in direction

The moon is orbiting within a circular path of radius $r$ with constant speed $v$.

Acceleration of the moon $a_c=\frac{v^2}{r}=constant$

Acceleration (centripetal) of the moon always acts towards the centre of earth and thus it continuously changes its direction at every instant.

Hence the magnitude of acceleration is constant but it is variable in direction.