 # Let’s Get Physics-l: Newton’s Second Law

The second instalment in this thrilling trilogy! Let’s get to it, shall we! (I’ll now refrain from using exclamation marks…)

Newton’s Second Law states that:

The resultant force of an object is proportional to the rate of change of momentum of the object, and the momentum change takes place in the direction of the force.

This law effectively states the total force upon an object will increase/ decrease as rate of change of momentum changes. The momentum also gains direction from the direction of the force. I have to admit, this law is a little less straight forward than the first and third but I’ll try my best to explain it.

An equation that underpins Newton’s Second Law is:

# F = ma

• F – Resultant Force (N)
• m – Mass (kg)
• a – acceleration (ms^-2)

From this, we can begin to make more sense of the second law. Force causes an object to accelerate in a certain direction which is effectively what is going on when we say that the momentum change takes place in the direction of force. For momentum to change the velocity must increase (Easier than altering the mass) via acceleration which is where we see the link strengthen (Or, at least, I do). The Resultant force causes acceleration which consequently changes the velocity and the momentum in the direction of the force.

Summary

• Newton’s Second Law – The resultant force of an object is proportional to the rate of change of momentum of the object, and the momentum change takes place in the direction of the force.
• F = ma – Helps to explain the law
• Resultant force – causes acceleration
• Acceleration – causes increase in velocity over time
• Increased Velocity over time – change of momentum over time
• Change of momentum over time – Newton’s Second Law

I hope that explanation was understandable (I couldn’t think of a relevant superhero example which, I imagine, for some may be a relief) and that you now have a better grasp of Newton’s Second Law. As always, please leave all thoughts, questions, feedback and requests in the comment section and I will get back to you as soon as I can. Thank you.