The law of conservation of energy states that energy cannot be created or destroyed, but it can be transferred.

Friction can cause energy to dissipate into the surroundings by heating.

Work is done whenever a force makes an object move. The amount of work is force multiplied by distance moved in the direction of the force.

The unit for measuring energy is the joule (J) which is the same as the unit for measuring energy.

A thousand joules is called a kilojoule (kJ).

Work done calculations (W = F × s)

Physics

Power calculations (P = W/t)

Calculating efficiency (in terms of useful output energy transfer)

Calculating the energy of moving objects (E=1/2mv2)

The energy of objects in a gravitational field (E=mgh)

Calculating energy changes - with complex examples (E)

Stretching a spring practical

Stretching a spring analysis and calculations (F=kx)

Calculating the energy of springs (E = 1/2 kx²)

In the Forces make things change unit, they will build on this knowledge to learn how to combine forces in two dimensions, how to calculate acceleration from a resultant force and how to calculate forces in collisions and explosions.

In the Measuring and calculating motion unit, pupils learnt how to measure and calculate velocity and acceleration, and how to interpret displacement-time and velocity-time graphs. 

This unit covers energy changes in systems through heating, forces, and electrical work. It includes energy storage, efficiency, and transfer methods like insulation. Emphasis is on calculating energy, conducting experiments, interpreting data, and communicating findings accurately.

Energy of moving objects

The energy is used up, so there is none left.

The energy spreads out into the surroundings.

The energy is transferred into a thermal store.

The energy is transferred into a chemical store.

Which two statements describe what happens to energy when it dissipates?

240 J of energy is transferred from a chemical store to both a gravitational store and a thermal store. If 80 J is transferred to the gravitational store, how much is transferred to the thermal store?

Match the energy values on the left to the equivalent values on the right. 

A force of 600 N is used to lift a box above the ground. An identical box is moved three times as high by a force of 200 N. How much work was done lifting the second box compared to the first?

Put the statements in order of increasing work done on identical boxes, starting with the least work done. 

Aisha does 480 J of work pushing a crate 6 m along the floor. What is the size of the force that she pushed the crate with?

What is the name of the force that acts between two surfaces in contact and in the opposite direction to motion?

Which of these pieces of equipment can be used to measure the size of a force?

Which of these units is the size of a force measured in? 

Which of these forces is a contact force?

When a book is lifted and placed on a higher shelf, it has more energy in its {{}} store.

means an object may take part in a chemical reaction.

means an object may stretch and increase in length.

means an object has mass and is at a position above Earth's surface.

Match each energy store to the properties that an object has when there is energy in that store.

Starter Quiz

What is the name of the force that acts between two surfaces in contact and in the opposite direction to motion?