Chapter 8: Forces

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

a force that acts only between objects that are touching

Question 3

Non-Contact force

Answer 3

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

Question 4

Magnetic force

Answer 4

the force (a push or pull) that acts between magnets (including the 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 en

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

Atoms

Answer 7

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

Question 8

Negatively charged

Answer 8

having a lower electric potential

Question 9

Positively charged

Answer 9

having a higher electric potential

Question 10

Protons

Answer 10

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

Question 11

Neutrons

Answer 11

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

Question 12

Electrons

Answer 12

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

Question 13

Insulators

Answer 13

materials that do not allow electric charge to flow through them

Question 14

Conductors

Answer 14

materials that allow electric charge to flow through them

Question 15

Weight

Answer 15

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 16

Mass

Answer 16

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

Question 17

Terminal Speed

Answer 17

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 18

Air resistance

Answer 18

Is when the atmosphere pushes against an moving object

Question 19

Friction

Answer 19

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 20

Traction

Answer 20

a type of friction used to assist movement

Question 21

Lubricants

Answer 21

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 22

Buoyancy

Answer 22

a force which keeps objects floatin

Question 23

Surface Tension

Answer 23

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