Forces and Energy

Question 1

SI unit of force

Answer 1

Newton (N)

Question 2

definition of a force

Answer 2

push or pull that
changes shape/size of obj.
moves/stops obj.
changes direction of moving obj.
slows down/speeds up moving obj.

Question 3

what is used to measure force

Answer 3

force-meters
Newton meters (e.g. spring balance)

Question 4

what is a contact force

Answer 4

forces acted between 2 objects physically touching

Question 5

what is a non-contact force

Answer 5

forces acted between 2 objects not physically touching

Question 6

5 contact forces

Answer 6

resistance
spring force
tension
applied force
normal contact force

Question 7

3 non-contact forces

Answer 7

gravitational force
magnetic force
electrostatic force

Question 8

what is normal contact force

Answer 8

force exerted on object due to its contact with another object

Question 9

what is a gravitational field

Answer 9

region which a mass experiences a force due to gravitational attraction

Question 10

what is a gravitational field strength

Answer 10

gravitational force acting per unit mass

Question 11

formula of weight

Answer 11

W = mg (m = mass, g = gravitational field strength)

Question 12

SI unit for weight

Answer 12

Newton (N)

Question 13

what is friction

Answer 13

contact force that opposes motion or tendency for motion

Question 14

why is there friction

Answer 14

microscopically, surfaces/objects are rough jagged
as 2 surfaces slide against each other, they grind and drag to create friction

Question 15

3 benefits of friction

Answer 15

graphite pencil marks a mark on paper due to friction

warms hand when rubbed

friction between wheels and brakes slows down bicycles

Question 16

3 downsides of friction

Answer 16

wears out rubber tyres

engines/axels may lose energy due to friction

air resistance slows down car

Question 17

3 ways to reduce friction

Answer 17

lubricants
streamlined body to reduce air/water resistance
wheels/rollers/ball bearings (circular shape reduces C.S.A)

Question 18

what is resultant force

Answer 18

single force that has same effect as 2 or more forces acting together

Question 19

what is pressure

Answer 19

ratio of magnitude of force applied to area on which it is applied

Question 20

SI unit of pressure

Answer 20

Pascal (Pa) or N/m²

Question 21

formula of pressure

Answer 21

F (N)/A (m²)

Question 22

what is atmospheric pressure

Answer 22

pressure exerted by air in Earth’s atmosphere

Question 23

what is moment of a force

Answer 23

turning effect produced by force

Question 24

formula of moment of force

Answer 24

Moment of force = force (N) x perpendicular distance from pivot (m)

Question 25

SI unit of moment of force

Answer 25

Newton-metre (Nm)

Question 26

what is a pivot/fulcrum

Answer 26

point about which a force turns

Question 27

what does the Principle of Moments state

Answer 27

when obj. is in equilibrium sum of clockwise moments about any point is equal to sum of anti-clockwise moments about the same point

Question 28

what is energy

Answer 28

ability to do work

Question 29

SI unit of energy

Answer 29

Joule (J)

Question 30

what is potential energy

Answer 30

energy stored in a body due to its condition/position

Question 31

what is energy in action

Answer 31

energy that is in motion in a medium that has the ability to do work

Question 32

what is GPE

Answer 32

energy a body possesses due to its position relative to the ground

Question 33

# 3 points what does GPE depend on

Answer 33

mass (m) of obj. height (h) obj. is at gravitational field strength (g) obj.is in

Question 34

what is EPE

Answer 34

energy stored in elastic obj. when push or pulled

Question 35

what is CPE

Answer 35

energy which holds the atoms and molecules of a substance together this stored energy is released during chemical reactions

Question 36

what is NE

Answer 36

energy in the nucleus of an atom which holds protons and neutrons together this energy is released during nuclear reactions

Question 37

what is nuclear fission

Answer 37

breaking down of a larger nucleus by bombarding atom of a fuel with a neutron splitting it into 2 smaller nuclei and 2 or 3 neutrons to carry on reaction with another 2 or 3 fuel atoms (used in nuclear bombs and nuclear power stations)

Question 38

what is nuclear fusion

Answer 38

fusing of 2 small nuclei to form 1 larger, unstable nucleus giving off energy in the form of a fast-moving neutron (found in hydrogen bombs and stars)

Question 39

difference between CPE and NE

Answer 39

CPE: energy released when there is forming of bonds between atoms and molecules NE: energy released when there is change in atomic structure of an element

Question 40

what is KE

Answer 40

energy a body possesses due to its motion

Question 41

what does KE depend on

Answer 41

mass (m) of obj. speed (v) of obj.

Question 42

what is LE

Answer 42

energy which enables us to see and do work

Question 43

what is TE

Answer 43

energy which flows from a region of higher temperature to a region of lower temperature

Question 44

what is EE

Answer 44

energy made available by the flow of electric charges such as electrons and ions (most useful form of energy as it can convert to other forms easily)

Question 45

what is SE

Answer 45

energy produced by vibrations which can be detected by our ears

Question 46

# 3 points what does the Principle of Conservation of Energy state

Answer 46

energy cannot be created nor destroyed can be converted from 1 state to another/transferred from 1 body to another total amount of energy will be same before and after change or transfer

Question 47

3 ways to save energy

Answer 47

take public transport switch off appliances when not in use use fans instead of air-conditioners

Question 48

SI unit of work

Answer 48

Joule (J)

Question 49

# 2 points what conditions need to be met for work to be done

Answer 49

force acts on object object moves in same direction as force

Question 50

formula of work

Answer 50

W = F x d (F = force, d = distance moved by obj. in direction of force)