Chapter 8: Force

Question 1

Gravity

Answer 1

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 2

Contact force

Answer 2

The force that acts only between objects that are touching.

Question 3

Non- contact force

Answer 3

The forces that acts between objects even though the objects are not touching.

Question 4

Magnetic forces

Answer 4

The force (a push or pull) that acts between magnets (including earth) and magnetic objects.

Question 5

Electrostatic forces

Answer 5

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 6

Force

Answer 6

(noun) a push, pull or twist. Forces are measured in newtons (N). (verb) to push, pull or twist.

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

Atom

Answer 9

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

Question 10

negative electric charge

Answer 10

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

Question 11

Positive Electric Charged

Answer 11

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

Question 12

Protons

Answer 12

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

Question 13

Newtons

Answer 13

A unit of measuring force.

Question 14

Electrons

Answer 14

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

Question 15

Insulators

Answer 15

Materials that do not allow electric charge to flow through them

Question 16

Conductors

Answer 16

Materials that allow electric charge to flow through them

Question 17

Weight

Answer 17

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 18

Mass

Answer 18

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

Question 19

Newtons

Answer 19

The unit for measuring forces

Question 20

Terminal Speed

Answer 20

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 21

Air Resistance

Answer 21

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

Question 22

Friction

Answer 22

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 23

Lubricants

Answer 23

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 24

Traction

Answer 24

This type of friction, used to assist movement, is called traction.

Question 25

Buoyancy

Answer 25

A force which keeps objects floating

Question 26

Surface Tension

Answer 26

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