Easy dynamics question?

Question

On Planet X, a 50.0-kg barbell can be lifted by exerting a force of only 180N.

a) What is the acceleration of gravity on Planet X?

b) If the same barbell is lifted on Earth, what minimal force is needed?

When answering, please start with the basic Fnet = ma and go from there. Thanks! =D

Answer 1

I concur; start w/ F=ma.

(a) a = 3.6m/s^2

(b) F = 490N

Answer 2

The solution is simpler than you think.  

a) F=ma

we know the force that is exerted and the mass.  So:

180=50a

a=3.6 m/s^2

This is the acceleration due to gravity since the force given is that required to overcome gravity.  

b)The acceleration due to gravity on earth is always 9.8 m/s^2.  So:

F=ma

F=(50)(9.8)

F=490 N

This is minimal force required on earth.