Chapter 8 - Forces

Question 1

Force

Answer 1

A push, pull or twist

Question 2

Gravity

Answer 2

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

Question 3

Contact force

Answer 3

A force that acts only between objects that are touching

Question 4

Non-contact force

Answer 4

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

Question 5

Magnetic forces

Answer 5

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

Question 6

Electrostatic forces

Answer 6

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

Question 7

Temporary magnet

Answer 7

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

Question 8

Permanent magnet

Answer 8

A magnet that retains its magnetic effect for many years

Question 9

Repulsion

Answer 9

An opposing force

Question 10

Magnetic field

Answer 10

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

Question 11

Atoms

Answer 11

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

Question 12

Negatively charged

Answer 12

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

Question 13

Positively charged

Answer 13

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

Question 14

Protons

Answer 14

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

Question 15

Neutrons

Answer 15

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

Question 16

Electrons

Answer 16

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

Question 17

Insulators

Answer 17

materials that do not allow electric charge to flow through them

Question 18

Conductors

Answer 18

materials that allow electric charge to flow through them

Question 19

Weight

Answer 19

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

Question 20

Mass

Answer 20

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

Question 21

Newton

Answer 21

the unit for measuring forces

Question 22

Terminal speed

Answer 22

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

Question 23

Air resistance

Answer 23

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

Question 24

Friction

Answer 24

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

Question 25

Lubricant

Answer 25

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

Question 26

Traction

Answer 26

a type of friction used to assist movement

Question 27

Buoyancy

Answer 27

a force which keeps objects floating

Question 28

Surface Tension

Answer 28

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