Chapter 4, Problem 12Q

To determine

a)Is there any difference in force (or effort)required to lift the same object on the Earth and the Moon

b) Compare the force needed to throw a 2-kg object horizontally with a given speed on the Moon and on the Earth.

Answer to Problem 12Q

Solution:

a)The effort required to lift any object on the moon is 6 times lesser than that required on the Earth.

b)Force needed to throw a 2-kg object horizontally with a given speed on the Moon and on the Earth is same

Explanation of Solution

Given:

a)Mass of the object is 10kg

b)Mass of the object 2kg

To lift the object on the Earth requires a force the same size as its weight on Earth, which is given by

$\begin{array}{l}{F}_{Earth}=m\times g_{Earth}\\ \begin{array}{l}{F}_{Earth}=10\times 9.8\text{N}\hfill \\ F_{Earth}=98\text{ N}\hfill \end{array}\end{array}$

To lift the object on the Moon requires a force as its weight on the Moon

$\begin{array}{l}{F}_{Moon}=\text{ m}\times {\text{g}}_{Moon}\\ F_{Moon}=10\times 1.63\text{N}\\ F_{Moon}=16.3\text{ N}\end{array}$

The required force on the Moon is lesser than on the Earth. The effort required to lift any object on moon is 6 times lesser than that required on the Earth

(b)The horizontal accelerating force will be same on both Earth and Moon, because the mass of the object is same on both the Earth and the Moon, and both objects would have the same acceleration to throw them with the same speed. So according to Newton’s second law, the forces would have to be the same on Moon and Earth.