When an object moves through a liquid or a gas (a fluid), a drag force acts on it as it pushes particles out of its way.

The drag force on an object moving through air is called air resistance.

A streamlined object is shaped to reduce the drag forces acting on it.

The drag force on an object moving through water is called water resistance.

Streamlining

Science

Calculating speed

Measuring speed: practical

Measuring speed accurately

Reading distance-time graphs

Interpreting distance-time graphs

Changing speed

Newton's First Law

Comparing the speeds of different parachutes

Changing the speed of a parachute

In the Measuring and calculating motion unit, they will build on this knowledge to learn how to measure and calculate velocity and acceleration, and how to interpret velocity-time graphs. 

In the Forces unit, pupils learn to accurately describe and explain the actions of forces in a range of situations. 

This unit explores speed, forces, and motion, including effects on objects. It covers deriving equations, calculations, and distance-time graphs. Learn to use force arrows, identify balanced and unbalanced forces, and understand their impact on movement.

Moving by force

The force that acts when an object moves through a fluid.

Shaped so that it moves through liquids/gases more easily.

Match the key words with the explanations.

A car is travelling at high speed and opens a parachute. Which force increases when the parachute is opened?

Which features of a rocket-propelled car will allow it to reach a very high speed?

The weight of the skydiver has reached zero.

The drag of the skydiver has reached zero.

The weight of the skydiver is equal in size to drag force.

There are no vertical forces acting on the skydiver.

A sky diver jumps out of an aeroplane and speeds up until they reach a top speed. Which statements are true?

Four identical marbles are dropped from the same height into containers of different fluids.  Starting with the shortest time, put them into order of how long it takes them to reach the bottom.

Streamlining will reduce the mass of the lorry.

Streamlining increases the maximum driving force of the lorry.

A streamlined lorry will push fewer air particles out of the way per second.

A streamlined lorry will fit between air particles and avoid hitting them.

The drag force on the lorry will be less when it is streamlined.

Which of these statements explains why streamlining can increase the maximum speed of a lorry.

Which of these is used to mean the overall effect of a combination of forces, taking their direction into account?

Air resistance is an example of what kind of force?

When a resultant force acts on an object it can speed up or slow down. What word is used to describe an increase in speed?

The figure shows the forces on a van. What is happening to the van?

The size of the pull must be greater than the weight of the box.

The size of the pull must be less than the weight of the box.

The size of the pull is greater than the friction between the box and the floor.

The size of the pull is less than the friction between the box and the floor.

A person pulls on a stationary box. It starts moving towards them. Which statement is correct.

a stationary object will stay stationary.

a moving object keeps moving at the same speed in the same direction.

Which of these are parts of Newton's first law of motion? When there is no resultant force ...

Starter Quiz

Which of these is used to mean the overall effect of a combination of forces, taking their direction into account?