Question

Explain the law of motion needed to solve this problem and then solve it. On Planet Zorg, a 30 kg barbell can be lifted by only exerting a force of 180 N. What is the acceleration of gravity on Planet Zorg? Predict how the motion of this object would change if on Earth. Please help. I have no idea how to do this.

Answer 1

Law of Motion says that every object that moves uniformly tends to stay in that state unless a force is applied to it. Force is equal to the mass of that object multiplied by its acceleration:
F = m × a 
The unit of force is N = kg * m/s².

Q1: The acceleration of gravity on Planet Zorg is unknown:
a = ?

We know:
F = 180 N
m = 30 kg

Since F = m × a, then:
a = F/m
a = 180 N/30kg
a = 180 kg*m/s² / 30 kg
a = 6 m/s².
So, the acceleration of gravity on Planet Zorg is 6 m/s².

Q2: Force needed to change the motion of the object on the Earth is unknown:
F = ?

We know:
a = 9.8 m/s²
m = 30 kg

If F = m × a, then:
F = 30 kg × 9.8 m/s²
F = 294 N
So, force needed to change the motion of the object on the Earth is 294 N.