# physics

posted by
**arielle**
.

gravational force

deimos, a satellite of amrs, has an average radius of 6.3 km. If the gravational force between deimos and a 3.0 kg rock at its surface is 2.5x10(-2)N..what is the mass of deimos ?

Use the Universal Law of gravitation:

Force= G Mm/distance^2 Solve for M.

i did..but how do you solve for the second m ?

can anyone help ?!?!

i would really appreciate some help..anything can help...any physics experts ?

The littlm m is the rock mass, 3 kg. Big M is the mass of the Deimos

so it would be

2.5x10^.2=(6.67x10^-11)(3.0)(M)..divided by 6.3^2

so would the answer be 4.96x10^-15

is this correct?

There is no way that is correct.

m= Force*distance^2 /GM

= 2.5(10^-2)*6300^2 /((6.67x10^-11)*3)

I get almost 5 *10^15 kg

where does 6300 come from

is that 6.3 km=6300 ?