# Homework Help: Force of gravity between two objects

1. Mar 21, 2005

### pinkcarnations

hi i am stuck and dont know what to do next or if i am even on the right path. could someone help me please!!!!!!!!!!!!!!

my question is what is the force of gravity between two 100kg cars separated by a distance of 25m on an interstate highway?
I started out like this:

fg=Gm1m2+6.67 x 10-11Nm2 x (1000kg) (1000kg)
r2 kg2 (25m)2

G=6.67 x 10-11 Nm2
kg2

then i dont know what to do or if this is even close

thanks to anyone with the time to help.

2. Mar 21, 2005

### arildno

Just plug in the CORRECT values in the formula for F:
$$F=\frac{Gm_{1}m_{2}}{r^{2}},G=6.67*10^{-11}\frac{Nm^{2}}{kg^{2}},r=25m,m_{1}=m_{2}=100kg$$

Query:Check the value of the mass for each car; are you sure it is 100kg, rather than 1000kg?

3. Mar 21, 2005

### X-43D

It gives me an extremely small result. Something like 0.0000001 N. It makes sense btw.

Last edited: Mar 21, 2005
4. Mar 21, 2005

### arildno

Would you expect anything else?

5. Mar 21, 2005

### X-43D

No because gravity weaks considerably with the distance (action at a distance).