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 (W = F × s)

Combined science

Power (P = W ÷ t)

Efficiency (in terms of energy and power)

Calculating the energy of a moving object (Ek=½mv²)

The energy of an object in a gravitational field (EP=mgh)

Calculating energy changes (Ek and Ep)

Stretching a spring practical

Stretching a spring analysis (F=ke)

Calculating the energy of a spring (Ee = 1/2 ke²)

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 rate at which something changes is usually equal to the amount of change each second.

The unit for measuring power is the watt (W).

A thousand watts is called a kilowatt (kW).

Friction can cause energy to dissipate (spread out and becomes unusable) into the surroundings, causing them to heat up.

Efficiency is the fraction of energy supplied to an object or system that is usefully transferred by it.

The amount of energy usefully transferred by an object or system is the useful output energy transfer.

The total amount of energy transferred to an object or system is the total input energy transfer.

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

If an object is moving and has a mass, then there is energy in its kinetic store.

If two quantities are directly proportional, then as one increases, the other also increases at the same rate.

The energy an object has in its kinetic store is referred to as the object’s kinetic energy.

Objects have energy in the gravitational store because of their mass and their height.

Weight = mass × gravitational field strength, measured in newtons.

Gravitational field strength, g, is the force per kilogram caused by a gravitational field.

The energy stored in an object due to its height above the ground.

The principle of conservation of energy states that the total amount of energy at the end of a process is always the same as the total amount of energy at the beginning.

Friction or air resistance can cause energy to dissipate into the surroundings as heat.

The energy an object has in its gravitational store is referred to as the object’s gravitational potential energy.

The increase from the original length of a spring when it is stretched.

The stretch of a spring that returns to its original shape when the stretching force is removed.

The stretch of a spring as it is permanently stretched out of shape.

The largest extension of a spring before it is stretched out of shape.

A variable is directly proportional to another if it doubles or triples when the other one does the same.

A measure of how stiff a spring is and how hard it is to stretch or compress.

For elastic deformations, extension (or compression) is directly proportional to the force applied.

If an elastic object is stretched, compressed or bent out of shape, there is energy in the elastic store.

To make something smaller using forces, e.g. a spring gets shorter when it is compressed.

The increase in length from the original length of a spring when it is stretched.

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