Science Physics Investigation

2025 - Year 10

Calculate the net force on an object from two or more forces in one dimension using vector diagrams

Add forces in the same direction, subtract forces in opposite directions. The result is the net force shown by the arrow length and direction in the diagram.

Define the term inertia

Inertia is the tendency of an object to resist changes in its state of motion.

Describe the relationship between the mass of an object and its inertia

The greater the mass, the greater the inertia—heavier objects resist changes in motion more.

Define Newton's First Law

An object stays at rest, or moves at constant velocity, unless acted on by an unbalanced force.

Describe common examples of Newton's First Law in action

A book resting on a table stays still until pushed; a rolling ball slows down only because of friction.

Recognise a stationary object, or an object moving at constant velocity has balanced forces (no net force)

If forces are equal and opposite, they cancel out, resulting in no change in motion.

Define Newton's Second Law of Motion

The acceleration of an object is directly proportional to the net force and inversely proportional to its mass:

• F=ma

List examples when an unbalanced force produces an acceleration in the direction of that force

A car speeding up when the engine provides more force than resistance; a ball thrown upwards slowing down due to gravity; a person pushing a trolley and it moves forward.

Describe a force in terms of its magnitude and direction

A force has size (measured in newtons, N) and acts in a specific direction (vector quantity).

Recall that gravity causes objects to accelerate as they fall

Near Earth, objects fall with an acceleration of about 9.8 m/s² due to gravity.

Perform calculations using F=ma and weight=mg

Use F=ma to find force from mass and acceleration; weight is mass multiplied by gravitational acceleration (g).

Define Newton's Third Law of Motion

For every action force, there is an equal and opposite reaction force.

List examples where forces act as action and reaction pairs

A rocket pushes gases backward, gases push rocket forward; a swimmer pushes water backwards, water pushes swimmer forwards.

Explain how seat belts, air bags and crumple zones protect occupants of vehicles in a crash

They increase the time taken to stop, reducing the force on passengers by spreading out the deceleration.

When a crash happens, your body wants to keep moving forward (inertia). The seatbelt stretches slightly and spreads the stopping force across your chest and hips. This extra stretch means your body takes a bit longer to come to rest compared to hitting the dashboard instantly.

Because force = change in momentum ÷ time, more stopping time = less force on you.

What is a balanced force?

Forces on an object are equal and opposite, so they cancel out. The object does not change its motion. Example: A book sitting on a table – gravity pulls down, table pushes up.

What is an unbalanced force?

Forces on an object do not cancel. This causes the object to accelerate, slow down, or change direction. Example: Pushing a stationary car – your push is stronger than friction, so it moves.