Movement and Interactions: Forces, Energy and Electricity

Forces, energy and electricity

This topic brings together forces, energy and electricity. A resultant force changes how an object moves. Energy is stored and transferred but never created or destroyed. In electric circuits, current, potential difference and resistance are linked. Many questions here need calculations, so learning the equations matters.

Words for the physics

Learn these four terms before you work through the ideas.

Series and parallel

Circuits can be wired in two main ways.

Learn the equations, then use them

To reach the top grades, learn the key equations and use them: force equals mass times acceleration, and potential difference equals current times resistance. Always show your working in calculations.

Match the quantity to its unit

Match the term to its meaning

What does a resultant force do?

What happens when a resultant force acts on an object?

• It accelerates in the direction of the force.
• It keeps moving at a constant velocity.
• It always stops at once.
• It moves at a steady speed in the direction of the force.

Energy stores

Select the TWO energy stores.

• Kinetic energy.
• Gravitational potential energy.
• Electric current.
• Resistance.

Order the cause and effect

Put the steps in order to show how a car speeds up.

• The engine provides a driving force
• The driving force is bigger than friction, so there is a resultant force
• The car accelerates
• The car moves at a higher speed

Summarise the physics

A resultant _____ makes an object accelerate. The equation force equals mass times _____ links them. Energy is measured in _____ and is never created or destroyed, only transferred. In a circuit, potential difference equals current times _____. The kinetic energy _____ grows as an object speeds up.

Work out the acceleration

A resultant force of 12 newtons acts on a mass of 4 kilograms. What is the acceleration in metres per second squared? Divide the force by the mass.

Forces, energy and current

Tap the TWO statements that are TRUE.

• A resultant force causes acceleration
• Energy is conserved, never created or destroyed
• Current is measured in joules
• Balanced forces make an object accelerate
• Power is measured in newtons

Which energy store?

Decide which energy store is filling up in each case.

• A ball is lifted onto a high shelf
• A car speeds up along a road
• A spring is stretched

Explain the physics

Explain how a resultant force affects the motion of an object, and describe one energy transfer that takes place as it moves. Use the idea of a resultant force, and name the energy stores involved.

• Explain what a resultant force does to motion
• Name an energy transfer and the stores involved
• Explain how energy is conserved