FOCUS 4 - NEWTON’S LAWS

Question 1

Outline Newton’s 1st law of motion.

Answer 1

Law of Inertia

An object at rest will stay at rest and an object in motion will stay in motion (same speed and direction) unless acted upon by an unbalanced external force

e.g. stopping the car – the body leans forward – continues its initial motion

Question 2

Outline Newton’s 2nd law of motion.

Answer 2

Law of Force and Acceleration

When an unbalanced external force acts on an object its motion will change – it will accelerate

The greater the mass of an object, the greater the amount of force required to accelerate the object

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to the object’s mass

Acceleration = force / mass
Force = mass x acceleration

Question 3

Outline Newton’s 3rd law of motion.

Answer 3

Law of Action and Reaction

Forces occur between objects and always occur in pairs.
For every action force, there is an equal and opposite reaction force.
If object A exerts a force on object B, object B will exert an equal opposite force on object A.

Question 4

Describe qualitatively the relationship between force, mass and acceleration.

Answer 4

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to the object’s mass

Question 5

Relate quantitatively, force, mass and acceleration (F = ma), and apply to everyday situations.

Answer 5

Acceleration = force / mass
Force = mass x acceleration