The ultimate goal of dynamics is to explain why
objects move by understanding the forces acting on those objects.
One crucial formula allows us to accomplish this.
This formula relates the forces
acting on an object to the acceleration
of that object:
Newton's Second Law.
$$
\Sigma F = m a
$$

I kick and exert a net force of 200 N on a rock. The rock has a mass of 2 kg.
What is the acceleration of the rock?

Something is accelerating at a rate of 4 m/s^{2}.
It has a mass of 10 kg. What is the net force on this object?

The cabinet has a mass of 200 kg and I push it with a force of 20 N. That is the only
horizontal force on the cabinet. What is its acceleration? Include a unit!

An 80 kg person on a 20 kg bicycle is accelerating at 2 m/s^{2}. What is the net force on them?

When I exert a 100 N net force on my bookshelf, it accelerates at a rate of 4 m/^{2}.
What is the mass of the bookshelf?

A rocket has a mass of 1800 kg.
If the rocket thruster gives it a net force of 36000 N, how fast will it accelerate?

What is the mass of an object with an acceleration of 5 m/s^{2}
under a net force of 400 N? Include a unit!
Answers