Science chapter 9

Question 1

How do Forces in nature affect us?

Answer 1

Earthquakes, Tsunami, Volcanic Eruption

Question 2

What can a force be?

Answer 2

A force can be a ‘push’ or a ‘pull’.

Question 3

How is a force produced?

Answer 3

A force is produced when two objects touch each other or
when our body touches an object.

Question 4

Forces that are produced
when objects come into contact are called

Answer 4

Contact forces

Question 5

forces that are produced when objects do not touch each other are called?

Answer 5

Non-Contact Forces

Question 6

Types of contact forces

Answer 6

Friction and elastic force

Question 7

Friction is the…

Answer 7

Friction is the force that opposes
motion between two objects in
contact.

Question 8

Friction allows us to…

Answer 8

Friction allows us to hold on to
things without dropping them.

Question 9

What and what in our daily lives rely on friction?

Answer 9

walking and writing with a pencil

Question 10

Elastic force acts on …

Answer 10

a stretched
or compressed elastic object to
return it to its original shape.

Question 11

Types of non-contact forces?

Answer 11

Gravitational force, electrostatic force and magnetic force

Question 12

Magnetic force is …

Answer 12

the force exerted by a magnet on
magnetic materials such as iron and steel.

Question 13

Unlike poles(magnetic)/charges(electrostatic)…and the force is called

Answer 13

attract each other, attraction

Question 14

like poles(magnetic)/charges(electrostatic)…and the force is called

Answer 14

repel each other, repulsion

Question 15

Electrostatic force is the…

Answer 15

Electrostatic force is the force of attraction/repulsion
between particles due to their electric charges.

Question 16

Gravitational force is the…

Answer 16

force of attraction between
objects due to their masses.

Question 17

What is the gravitational force that the earth exerts on objects.

Answer 17

Our weight

Question 18

The SI unit of force is ?

Answer 18

Newton (N).

Question 19

We use a …. to measure force

Answer 19

spring balance

Question 20

What is mass?

Answer 20

Mass is the amount of matter in a body

Question 21

SI unit of mass is

Answer 21

Kilogram(kg)

Question 22

What is weight?

Answer 22

Weight is the gravitational force acting on an object

Question 23

SI unit of weight is

Answer 23

Newton(N)

Question 24

How to find weight?

Answer 24

Weight (W) = mass
(m) x gravitational
field strength of the
planet (g)

Question 25

Gravitational field strength tells us how strong

Answer 25

The Earth’s gravitational field will experience a gravitational force attracting it towards Earth’s centre.

Question 26

The ... the strength, the ... the gravitational force!

Answer 26

higher, greater

Question 27

Mass can be measured using a waht or waht

Answer 27

beam balance, electronic

Question 28

The beam balance compares

Answer 28

the gravitational force acting on an object with standard masses.

Question 29

Mass is ... of gravitational field strength

Answer 29

independent

Question 30

Weight is... on gravitational field strength

Answer 30

dependent

Question 31

Forces can change the state of

Answer 31

rest or motion of an object

Question 32

Forces can create what effect on an object

Answer 32

turning

Question 33

Forces can change the

Answer 33

size and/or shape of an object

Question 34

Forces can change the pressure on an object

Answer 34

pressure on an object

Question 35

Speed can be calculated using the formula

Answer 35

speed = dist travelled / time taken

Question 36

Pressure can be calculated using the formula

Answer 36

pressure = force / area

Question 37

The what you are in the water, the what the underwater pressure becomes.

Answer 37

deeper, greater

Question 38

the air pressure outside our bodies is ... by the air pressure inside our bodies. hence we are not killed by the atmospheric pressure

Answer 38

balanced

Question 39

The SI unit of energy and work done is

Answer 39

the joule (J).

Question 40

There is work done when

Answer 40

a force acts on an object and the object moves in the same direction as the force

Question 41

When work is done,

Answer 41

there will be transfer of energy from one object to another object.

Question 42

Work done is calculated using the formula

Answer 42

w = fs W = work done (in J); F = force applied (in N); s = distance moved in the direction of the force (in m).

Question 43

Types of energy in our daily lives

Answer 43

Potential energy (elastic, gravitational and chemical) Kinetic energy Electrical energy Thermal energy (or heat) Light energy Sound energy

Question 44

Potential energy is the

Answer 44

stored energy in a system.

Question 45

Types of potential energy

Answer 45

Chemical potential energy gravitational potential energy elastic potential energy

Question 46

Formula to find gravitational potential energy

Answer 46

m g h m = mass of object g = gravitational field strength (= 10 N/kg) h = height of object

Question 47

What is kinetic energy?

Answer 47

Kinetic energy is the energy possessed by moving object.

Question 48

Formula to find kinetic energy

Answer 48

Kinetic energy = 1/2 m v 2 where m = mass of object (in kg) v = speed of object (in m s−1)

Question 49

Principle of conservation of energy

Answer 49

energy cannot be be created nor destroyed, but can be converted from one form to another. The total energy in an isolated system is constant.

Question 50

An isolated system means that

Answer 50

the objects in the system only interact with one another and they have no interaction with any object outside the system.

Question 51

the total energy in the isolated system stays

Answer 51

constant

Question 52

non-renewable sources of energy

Answer 52

are limited and will run out one day

Question 53

some non-renewable sources of energy are

Answer 53

fossil fuels, diesel, petrol

Question 54

renewable sources of energy can be sustained or renewed indefinitely.

Answer 54

can be sustained or renewed indefinitely.

Question 55

some renewable sources of energy are

Answer 55

solar energy, hydroelectric energy, wind energy, geothermal energy, biofuels and nuclear energy