Overview of Forces and Newton’s Laws of Motion – Lesson Summary

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Learning Objective

In this lesson we will review forces and introduce Newton’s three laws of motion.

Learning Outcomes

By the end of this lesson you will be able to:

  • Define what a force is and explain how forces can affect objects.
  • Distinguish between push, pull and twist forces.
  • Name the units used for measuring forces.
  • Distinguish between balanced and unbalanced forces and explain how net force is calculated.
  • Give an overview of Newton’s three laws of motion.

 
overview of forces and newtons laws of motion lesson contents

(Image: NASA/Bill Ingalls, Wikimedia Commons)

Lesson Topics

1 | Forces

2 | Types of Forces

3 | Measuring Forces

4 | Balanced and Unbalanced Forces

5 | Newton’s Laws of Motion

6 | Summary

Lesson Summary

  • A force is any interaction that causes a change in the speed, direction or shape of an object.
  • Forces are measured in newtons (N).
  • They are vector quantities, which means their magnitude must be accompanied by a direction.
  • Forces can be grouped into three categories, depending on the direction of the force.
  • A push force moves an object away from the source of the force.
  • A pull force moves an object towards the source of the force.
  • A twist force rotates an object around a fixed point.
  • Net force is the sum of all forces acting on an object.
  • Balanced forces result in a net force that equals zero; therefore, they do not cause a change in motion.
  • Unbalanced forces result in a net force that does not equal zero; therefore, they cause a change in motion.
  • Newton’s laws of motion describe the relationship between the motion of an object and the forces acting on it.
  • They state that:
  • Objects move in a straight line at a constant speed unless acted upon by an unbalanced force.
  • The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
  • For every action, there is an equal and opposite reaction.

 
unbalanced forces tug-of-war

(Image: snyGGG, Adobe Stock)

(Header image: Blue Planet Studio, Adobe Stock)