Question

An object weighs 100 newtons on earth.What is its weight on the moon?

Answer 1

20 N

Step-by-step explanation:

Consider that earth's acceleration due to gravity is approximately 9.81 m/s^2. Also consider that the moon's acceleration due to gravity is about 1.62 m/s^2. Using these two values, we can easily find the weight of the object on the moon, given that the object weighs 100 N, and that F = ma.

First, let's break it up.

100/9.81 =

10.193679918450561 kg

10.193679918450561*1.62 =

16.513761467889908 N

≈ 20 N (with one significant digit, since that is the least amount of sig figs in the problem)

Answer 2

a) The gravitational acceleration at the surface of the Moon is g moon=1.67 m/s

2

The ratio of weights (for a given mass ) is the ratio of g-values, so

W

moon

​

=(100N)(1.67/9.8)=17N.

(b) For the force on that object caused by Earth's gravity to equal 17 N, then the free fall acceleration at its location must be

ag

​ =1.67m/s

2

. Thus , .

ag

= r 2

Gm

E

⇒

a

g

Gm

=1.5×10

7

m

So the object would need to be a distance of r/R

E

​

=2.4 "radii" from Earth's center.