Newton's second law of motion

Everything You Need in One Place

Homework problems? Exam preparation? Trying to grasp a concept or just brushing up the basics? Our extensive help & practice library have got you covered.

Learn and Practice With Ease

Our proven video lessons ease you through problems quickly, and you get tonnes of friendly practice on questions that trip students up on tests and finals.

Instant and Unlimited Help

Our personalized learning platform enables you to instantly find the exact walkthrough to your specific type of question. Activate unlimited help now!

Get the most by viewing this topic in your current grade. Pick your course now.

  1. Introduction to Newton's second law
    Meaning of Newton's second law
    Newton's second law formula
    Newton, the unit of force
  1. Applying Newton's second law
    1. What is the unbalanced force required to accelerate a 1370 kg car at 4.25 m/s2m/s^{2}?
    2. What is the unbalanced force required to bring a 995 kg car travelling at 11.5 m/s to a stop in 30.0 m?
    3. An apple falls from a tree.

      i. What is the force of gravity acting on a falling 0.200 kg apple?

      ii. If the apple is accelerated downwards at 9.53 m/s2m/s^{2}, find the force of air resistance acting on the apple.

Topic Notes
In this lesson, we will learn:
  • Newton's second law of motion
  • Problem solving with Newton's second law of motion


  • Newton's second law: If a net force acts on an object, its velocity changes. The acceleration is proportional to the magnitude of the net force, and inversely proportional to the mass, or Fnet=ma\vec{F}_{net}=ma
  • The force of gravity acting on an object is Fg=mg\vec{F}_{g}=mg, where gg is acceleration due to gravity (9.81 m/s2 [down])
Newton's Second Law

ΣF=Fnet=ma\Sigma \vec{F} = \vec{F}_{net} = m\vec{a}

ΣF:\Sigma \vec{F}: sum of all forces, in newtons (N)

Fnet:\vec{F}_{net}: net force, in newtons (N)

m:m: mass, in kilograms (kg)

a:\vec{a}: acceleration, in meters per second squared (m/s2)(m/s^{2})