Acceleration of gravity on an unknown planet.

[flysae]

Homework Statement

A 92 kg man weighs 189 Newtons on the surface of an unknown planet. What ist he acceleration of gravity on this planet?

Basically, I thought the formula to finding the gravitational force was
G(gm)/r^2, but I'm missing the distance that the man from the planets center is. I don't know where the 189 Newtons fit in.

Homework Equations

G = (gm)/r^2

The Attempt at a Solution

G = (gm)/r^2
G = (6.67x10^-11nm^2/kg^2)(92kg)/r? What is R? I'm totally lost.

Thank you, appreciate it!

 

[Doc Al]

It's simpler than all that. If you knew the value of "g" on the planet, how would you find the weight?

 

[nlightner]

I would like to first clarify that the formula you mentioned, G = (gm)/r^2, is actually the formula for calculating the gravitational force between two objects. The force of gravity is given by the equation F = ma, where F is the force, m is the mass, and a is the acceleration due to gravity.

In this scenario, we are given the mass of the man (m = 92 kg) and the force of gravity on him (F = 189 N). We can use the formula F = ma to solve for the acceleration due to gravity (a).

F = ma
189 N = (92 kg)a
a = 189 N/92 kg
a = 2.05 m/s^2

Therefore, the acceleration of gravity on this unknown planet is 2.05 m/s^2.

To find the distance (r) from the center of the planet, we would need more information such as the radius or the gravitational constant of the planet. Without this information, we cannot calculate the distance.

I hope this helps clarify your confusion. Remember to always check your equations and units to make sure they are consistent and to use the correct formulas for each scenario. Keep up the good work!