Forces
The forces are with us
| Word | Pronunciation | Meaning |
| air resistance | A force that tries to slow things down that are moving through air. It is a type of friction. | |
| drag | Air resistance and water resistance are both sometimes called drag. | |
| force | A push or a pull. | |
| force meter | Piece of equipment containing a spring, used to measure forces. | |
| friction | A force that tries to slow things down when two things rub against each other. | |
| gravity | The force of attraction between any two objects. The Earth is very big and so has strong gravity that pulls everything down towards it. | |
| magnetism | A force that attracts objects made out of iron. | |
| newton (N) | The unit of force. | |
| newton meter | Another name for a force meter. | |
| speed | How fast something is moving. Often measured in metres per second (m/s). | |
| static electricity | A force which attracts things with extra electrical charges on them. | |
| upthrust | A force that pushes things up. | |
| water resistance | A force that tries to slow things down that are moving through water. It is a type of friction. |
That floating feeling
| Word | Pronunciation | Meaning |
| density | The amount of mass that 1cm3 of a substance has. Measured in g/cm3. | |
| upthrust | A force that pushes thing up. |
Balancing act/Hooked!/Weighing in
| Word | Pronunciation | Meaning |
| balanced forces | When two forces are the same strength, but working in opposite directions. | |
| gram | A unit for measuring mass (g). | |
| gravity | The force of attraction between any two objects. The Earth is very big and so has a large gravity pulling everything down towards it. | |
| kilogram | A unit for measuring mass (kg). There are 1000 g in 1 kg. | |
| mass | The amount of matter that something is made of. Measured in grams (g) and kilograms (kg). Your mass does not change if you go into space or to another planet. | |
| newton | The unit of force (N). | |
| stationary | Not moving. | |
| unbalanced forces | When two forces working in opposite directions are not the same strength. | |
| weight | The amount of force with which gravity pulls something towards the Earth. It is measured in newtons (N). |
Friction
| Word | Pronunciation | Meaning |
| lubricant | loo-brick-ant | A substance (normally a liquid) used to reduce friction. |
| water resistance | A force that tries to slow things down that are moving through water. It is a type of friction. |
The need for speed
| Word | Pronunciation | Meaning |
| braking distance | The distance a car travels while the brakes are trying to stop it. | |
| distance/time graph | A graph that shows how far and how fast something travels during a journey. | |
| kilometres per hour (km/h) | Units for speed when the distance is measured in kilometres and the time is measured in hours. | |
| metres per second (m/s) | Units for speed when the distance is measured in metres and the time is measured in seconds. | |
| miles per hour (mph) | Units for speed when the distance is measured in miles and the time is measured in hours. | |
| speed | How fast something is moving. Often measured in metres per second (m/s). | |
| stopping distance | The distance a car moves while it is stopping. The stopping distance is equal to the thinking distance and the braking distance added together. | |
| thinking distance | The distance a car travels while the driver is deciding to press the brake pedal. |
Faster and faster
| Word | Pronunciation | Meaning |
| accelerate | ack-sell-er-ate | Change speed. |
| air resistance | A force that tries to slow down things that are moving through the air. It is a type of friction. | |
| balanced forces | When two forces are the same strength, but working in opposite directions. | |
| friction | A force that tries to slow things down when two things rub against each other. | |
| unbalanced forces | When two forces working in opposite directions are not the same strength. |
Drag act
| Word | Pronunciation | Meaning |
| drag | Another name for air resistance or water resistance. | |
| streamlined | Giving something a smooth shape to reduce the air resistance or water resistance. | |
| water resistance | A force that tries to slow down things that are moving through water. It is a type of friction. |
Hitting the limit
| Word | Pronunciation | Meaning |
| distance–time graph | A graph that shows how far something has moved in a certain time. | |
| terminal velocity | The maximum speed of an object. Usually only applies to falling objects when the downward force is balanced by drag. |