The Moon’s mass is of Earth’s mass and its radius is of Earth’s radius.

PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics

Problem

The Moon’s mass is

\tfrac1{81}

of Earth’s mass and its radius is

\tfrac14

of Earth’s radius. (i) Calculate the acceleration due to gravity on the Moon’s surface. Take

g_{\text{Earth}} = 9.8\,\text{m/s}^2

. (ii) A student on the Moon throws a ball vertically upward so that it just reaches a height of

20\,\text{m}

. Find the initial speed with which the ball was thrown. (iii) If the ball has a mass of

0.5\,\text{kg}

, compute its weight on the Moon and on Earth.