Chapter 8 - Forces Flashcards Preview

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Flashcards in Chapter 8 - Forces Deck (28):
1

Force

A push, pull or twist

2

Gravity

the force of attraction that exists between any two bodies in the universe that have mass. The gravity at the Earth’s surface is the pull on objects near its surface towards the centre of the Earth

3

Contact force

A force that acts only between objects that are touching

4

Non-contact force

A force that acts between objects even though the objects are not touching

5

Magnetic forces

the force (a push or pull) that acts between magnets (including the Earth) and magnetic objects

6

Electrostatic forces

A non-contact force of electric charges at rest. We experience electrostatic forces when we pull off a jumper and our hair stands on end

7

Temporary magnet

a magnet that stays magnetic only while it touches a permanent magnet, or one that is magnetic for a very short time

8

Permanent magnet

A magnet that retains its magnetic effect for many years

9

Repulsion

An opposing force

10

Magnetic field

a map of lines showing the size and direction of a magnetic force. The size of the force is shown by how close together the lines are. The direction at any point is given by the direction in which the north pole of a magnet would face

11

Atoms

a very small particle that makes up all things. Atoms have the same properties as the objects they make up

12

Negatively charged

the charge on an atom or object with more electrons than protons

13

Positively charged

the charge on an atom or object with fewer electrons than protons

14

Protons

tiny, but heavy, particle found in the nucleus of an atom. Protons have a positive electrical charge

15

Neutrons

tiny, but heavy, particles found in the nucleus of an atom. Neutrons have no electrical charge

16

Electrons

very light, negatively charged particles inside an atom. Electrons move around the central nucleus of an atom

17

Insulators

materials that do not allow electric charge to flow through them

18

Conductors

materials that allow electric charge to flow through them

19

Weight

a measure of the size of the gravity force pulling an object towards the centre of a massive body, such as the Earth. The weight of an object depends on the object’s mass

20

Mass

a measure of the amount of material in an object of substance

21

Newton

the unit for measuring forces

22

Terminal speed

the constant speed reached by a falling body. A body reaches terminal speed when the force of gravity pulling it down is balanced by the air resistance pushing against it

23

Air resistance

the force of air pushing on an object as the object moves through the air

24

Friction

a force that acts against the movement of an object. It occurs between any surfaces that are touching and trying to move past each other

25

Lubricant

substance with large particles that can slide easily over each other. Lubricants are used between surfaces that rub against each other to reduce wear and increase motion between the surfaces

26

Traction

a type of friction used to assist movement

27

Buoyancy

a force which keeps objects floating

28

Surface Tension

the ‘firmness’ of the surface of a liquid created by the attraction between particles at the surface. The surface acts like an elastic skin