# 4.5.6.2.1

4.5.6.2.1 Newton’s First Law

# 4.5.6.2.1 Newton’s First Law

## Content

Newton’s First Law:

If the resultant force acting on an object is zero and:

• the object is stationary, the object remains stationary
• the object is moving, the object continues to move at the same speed and in the same direction. So the object continues to move at the same velocity.
• So, when a vehicle travels at a steady speed the resistive forces balance the driving force.
• So, the velocity (speed and/or direction) of an object will only change if a resultant force is acting on the object.
• Students should be able to apply Newton’s First Law to explain the motion of objects moving with a uniform velocity and objects where the speed and/or direction changes.
• (HT only) The tendency of objects to continue in their state of rest or of uniform motion is called inertia.

MS 3a Understand the symbols: = < << >> >~

MS 3b Change the subject of an equation

MS 3c Substitute numerical values into algebraic equations using appropriate units for physical quantities

MS 1d Make estimates of the results of simple calculations

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