# Homework Help: Force of gravity

1. Jan 21, 2007

### soulja101

1. The problem statement, all variables and given/known data
The force of gravity experienced by a person on earth is 750N. What is the force of gravity on the same person aat each of the following distances, in multiples of the Earth's radius from the centre of earth?

2. Relevant equations

FG=mg

3. The attempt at a solution
The answers are A)3 B)10 C)22
750N/9.8N/kg
=76.53

2. Jan 21, 2007

### hover

If you want to find the force of gravity at different distances use the equation-
F=G* mass1*mass2/distance^2

G=gravitational constant or 6.67*10^-11
masses in kilograms
distance in meters
the final force in newtons

3. Jan 21, 2007

### D H

Staff Emeritus
hover:
The universal gravitational constant is not needed to answer this question. (Besides, you didn't give the mass of the Earth.)

Soulja:
Using F=mg is not correct; hover's equation is correct.

You know the force at one Earth radius. Using $$F = \frac{G m_1 m_2}{r^2}$$, can you determine the relation between the forces if the masses remain constant but the distance is varied?

4. Jan 21, 2007