A force acting upwards due to pressure is an upthrust.

Water is displaced (moved) when an object floats on it or sinks in it.

A displacement can is used to find the volume of water displaced by objects when they float or sink.

If the density of an object is less than the density of water, it will float.

Floating, mass and shape

Science

Gravitational force and weight

Stretching springs

Hooke's law

Stretching rubber

The force of a floor

Levers

Turning forces

Pressure

Pressure at different depths and heights

In the Particle explanations of density and pressure unit, pupils will build on this knowledge to learn how the arrangement and movement of particles in solids, liquids and gases explain density, pressure, floating and convection.

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

This unit explores forces, deformation, Hooke’s Law, moments, and work done. It covers pressure in liquids, atmospheric pressure, upthrust, and equilibrium, as well as simple machines and force-extension relationships, highlighting how forces affect motion, friction, and object deformation.

Hidden forces

A force acting on a floating object due to water pressure.

Used to find the volume or mass of displaced water.

All of the ship is floating on the water.

only the part of the ship above the water is floating

only the part of the ship below the water is floating

A cargo ship is travelling on water. Which of these statements is correct?

The boat will float at the same height in the water.

A wooden boat floats in shallow water. Which of these describes what will happen when it is placed in deeper water?

it can push its own mass of water out of the way.

it pushes less than its own mass of water out of the way.

Which of these is the correct condition for something to be able to float?

The table shows the mass of objects and the mass of water they displace. Which objects float?

The foil boat floats because aluminium is less dense than water.

The foil boat floats because aluminium is more dense than water.

The foil boat floats because the boat's density is less than that of water.

The ball sinks because its density is lower than that of water.

The ball sinks because its density is higher than that of water.

A pupil makes a boat from aluminium foil. It floats on water. When they scrunch it up into a ball it sinks. Why?

the size of force needed to lift or support it

Which is the best definition of the weight of an object?

Which is the best definition of the mass of an object?

not all of the forces are shown in the figure

The figure shows two forces acting on a toy boat on the surface of water. Which statements are correct?

A balance is used to measure the mass of a sample of water. If the mass of the water is 320 g, what is this mass in kilograms?

A sample of water has a mass of 0.5 kg. What is its approximate weight on Earth?

There are no vertical forces acting on the ship.

There is a downwards gravitational force acting on the ship.

There is an upwards force acting on the ship.

There is a resultant force acting on the ship.

A cruise ship is stationary and floating on the surface of the water. Which statements are correct?

Floating, mass and shape

Lesson outcome