4.9 Newton’s Laws of Motion

Question 1

What does Newton’s first law of motion state?

Answer 1

The velocity of an object will not change unless a resultant force acts on it

Question 2

What does Newton’s second law of motion state?

Answer 2

Acceleration of an object is proportional to the resultant force acting on it:
resultant force = mass x acceleration

Question 3

What is resultant force and what is it measured in?

Answer 3

• the resultant force is the vector sum of all of the forces
• the resultant force is always measured in newtons

Question 4

What is mass always measured in?

Answer 4

Kilograms

Question 5

What is the direction of acceleration the same as and what is acceleration measured in?

Answer 5

• acceleration is always in the same direction as the resultant force
• it is measured in ms^-2

Question 6

What is Newton’s third law of motion?

Answer 6

If an object A exerts a force on object B, then object B exerts an equal and opposite force on object A

Question 7

When does Newton’s third law apply?

Answer 7

In all situations and to all types of force, but the pairs of force are always the same type