4.1.16

Newton's Laws

Test yourself

Newton’s 1st Law

Newton's 1st Law says that the velocity of an object will only change if a resultant force is acting on the object. This applies to a stationary (still) or moving object.

Illustrative background for Stationary (still)Illustrative background for Stationary (still) ?? "content

Stationary (still)

  • If an object is stationary (not moving) and there is no resultant force acting on it, it will stay stationary.
Illustrative background for MovingIllustrative background for Moving ?? "content

Moving

  • If an object is moving and there is no resultant force acting on it, the object will continue moving in the same direction at the same speed.
    • This means that the object will continue moving at the same velocity.
    • This also means that the velocity of an object will only change if a resultant force is acting on the object.

Newton's 2nd Law

A force may cause a mass to accelerate. This acceleration can be a change in speed, a change in direction or a change in both speed and direction. This is Newton's 2nd Law.

Illustrative background for Resultant forceIllustrative background for Resultant force ?? "content

Resultant force

  • The resultant force is the sum of all of the forces acting on an object.
  • The change in an object’s motion is caused by the resultant force.
  • If the forces acting on an object are unbalanced (not equal) it means that a resultant force is acting on the object.
Illustrative background for Resultant force equationIllustrative background for Resultant force equation ?? "content

Resultant force equation

  • A resultant force causes an acceleration.
  • The acceleration can be calculated with this equation.
  • Resultant force (F) = mass (m) x acceleration (a).
  • This is Newton's 2nd Law.
  • Remember that the resultant force is the vector sum of all forces. You need to take into account their directions.

Jump to other topics

1Measurements & Errors

2Particles & Radiation

3Waves

4Mechanics & Materials

5Electricity

6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

Go student ad image

Unlock your full potential with GoStudent tutoring

  • Affordable 1:1 tutoring from the comfort of your home

  • Tutors are matched to your specific learning needs

  • 30+ school subjects covered

Book a free trial lesson