Duration: 02:40

Examining the problems caused by changes in atmospheric pressure and temperature when planning a helium balloon ride to the edge of space.

Duration: 03:30

Aerodynamic principles are used to reduce the drag or air resistance on a cycle rider.

Duration: 01:26

A demonstration of the effects of air pressure.

Duration: 01:59

A brief explanation of what air resistance is and how it can be reduced.

Duration: 04:16

Investigating what makes a comfortable chair by changing the net force exerted on a seat and observing the change in pressure.

Duration: 02:36

A model showing how an avalanche occurs due to different types of snow fall over a period of time.

Duration: 02:50

Footage of a scientist exploring his sense of balance on board the zero gravity 'vomit comet' training aeroplane for astronauts.

Duration: 01:17

A description of contact forces illustrating balanced and unbalanced forces when sitting on a chair.

Duration: 02:36

An explanation of the difference between balanced and unbalanced forces, using a cyclist as an example.

Duration: 02:02

Balanced and unbalanced forces are demonstrated using eggs, books and seat cushions. The concept of equilibrium is introduced.

Duration: 5:03

Greg Foot investigates why quicksand is dangerous and the forces involved that make it so difficult to escape from.

Duration: 05:28

Presenter Greg Foot investigates what would happen if an asteroid collided with Earth. He looks at the risks involved, calculates how much energy would be transferred and explains how our atmosphere protects from all but the largest asteroids.

Duration: 03:43

Brian Cox explains the effects changes in gravity have on the body.

Two balls of similar size but different mass are dropped and observed landing at the same time. The effect of air resistance is explained using a hammer and a feather, along with NASA footage.

Duration: 00:45

How the buoyancy of water in a salt water pool helps patients to exercise without exerting their full weight on injured joints.

Duration: 02:00

A demonstration of how to make a film cannister rocket.

Duration: 02:51

Describes the relationship between force, pressure and contact area. The imprint of a ballerina on points is compared to the track marks of a Scorpion tank.

Duration: 02:33

Testing the sharpness of two knives. The relationship between the force, pressure, and surface area is explained.

Duration: 01:19

The relationship between pressure, force and contact area, using footwear as an example.

Duration: 02:08

Explains how the hairs of a stinging nettle can pierce skin more easily than a pin.

Duration: 117

The causes and effects of friction are described.

Duration: 02:10

An introduction to friction, using a cyclist as an example. Some ways in which friction can be increased between tyres and the road are given.

Duration: 05:20

The gravitational field interactions between Jupiter and its moons cause tremendous changes to the surface of Io, one of its moons.

Duration: 00:34

A demonstration of a feather and a hammer falling at the same rate on the Moon in the absence of air resistance.

Duration: 01:00

Why does liquid travel up a drinking straw? It's not just because you suck it!

Duration: 00:49

An explanation of how helium balloons float.

Duration: 02:36

A demonstration of how the frictional force exerted by an object is affected by the surfaces in contact with each other.

Duration: 01:12

Frictional forces exist in non-solids and change with the shape of an object.

Duration: 02:28

A demonstration of how the frictional force between a curling stone and the ice depends on the type of ice.

Duration: 3:59

Presenter Greg Foot investigates the question that if the whole population of the world jumped at the same time, whether it could cause an earthquake and if it would affect the speed at which the Earth turns on its axis.

Duration: 01:08

A brief explanation of how friction can be useful and not useful, using a bike as an example. Ways of increasing and reducing friction are given.

Duration: 02:45

A demonstration of the increasing frictional force of an object as a driving force is applied against it.

Duration: 03:22

What happens to balloons in a decompression chamber?

Duration: 02:21

Presenter Dr Yan demonstrates the power of friction with some paperbacks and strong members of the public.

Duration: 04:26

A Norwegian submarine is stranded 80m underwater. The presenter is on-board a Royal Navy rescue submersible for a navel exercise as it docks with the submarine. The concept of pressure differentials is explained.

Duration: 03:41

Presenter Jem climbs a sheer BBC building with gloves built from ordinary vacuum cleaners.

Duration: 02:35

A discussion of the principles of buoyancy and how to make a Cartesian diver.

Duration: 02:08

A practical demonstration showing how you can investigate the Coriolis effect using your bathroom sink.

Duration: 03:38

A practical demonstration using a bicycle pump to put bubbles under high and low pressure.

Duration: 03:32

Simulating the effects of fire on air pressure when the amount of available oxygen changes. A backdraught occurs as an oxygen-starved fire is suddenly given a new supply of oxygen.

Duration: 03:11

How big is the solar system? A description of the extent of the Sun's gravitational influence on other objects such as comets.

Duration: 02:46

The Russian Venera 4 probe did not withstand the high atmospheric pressure to reach the surface of Venus before being crushed.

Duration: 03:41

The upthrust on a model placed in fresh water and salt water is compared. One model floats and the other sinks.

Duration: 03:27

How atmospheric air pressure is used to help pump water from an open reservoir to a higher level.

Duration: 02:43

A practical demonstration using a bicycle pump to make a rocket out of a plastic bottle.

Duration: 00:47

Space, the moon landing and different planets are used to talk through gravity.

Duration: 01:29

A demonstration of the effect of upthrust on masses in air and water and the effect of buoyancy on weights of different density.

Duration: 01:34

A demonstration that mass and weight do not affect acceleration due to gravity.

Duration: 04:11

James Burke takes a zero gravity flight in the special plane used by the NASA astronauts.