Forces

Question 1

Contact forces

Answer 1

friction

Question 2

non contact force

Answer 2

magnetic force and gravitational force

Question 3

S.I unit

Answer 3

newton

Question 4

instrument to measure force

Answer 4

spring balance

Question 5

effect of force

Answer 5

• makes an object speed/slow/stop
• change direction
  -change speed
  -cause a stationary object to move

Question 6

gravity

Answer 6

-pull object
- causes objects to have weight
- stronger the pull, stronger the weight

Question 7

gravity formula

Answer 7

Weight = mass X gravity
- 10N every 1kg of object

Question 8

diff between mass and weight

Answer 8

-mass is the amt of matter in the object
- weight is the measurement of gravity on an object

Question 9

location for gravity

Answer 9

-gravity pull of the earth is stronger then the moon, so weight of an object is higher on earth
- mass is NOT affected
- weight changes

Question 10

Friction

Answer 10

-when two objects rub against each other
-slows down an object

Question 11

examples of friction

Answer 11

walking, running, writing

Question 12

cons of friction

Answer 12

wear and tear, heat productions

Question 13

pressure

Answer 13

force acting on an area

Question 14

S.I unit of pressure

Answer 14

Pascal (Pa)

Question 15

what does a smaller area of contact do?

Answer 15

-smaller area of contact
- high pressure
-easily exerted

Question 16

what does a larger surface area do?

Answer 16

-larger area of contact
- low pressure
- difficult to exert

Question 17

formula of pressure

Answer 17

pressure= force (N) / area(m2)

Question 18

boot studs

Answer 18

• smaller area
• exert greater pressure
• prevent slipping

Question 19

skis

Answer 19

-larger area
- reduce pressure
- easier to ski

Question 20

key word for pressure

Answer 20

HIGH pressure
LOW pressure

Question 21

Liquid (Pressure)

Answer 21

the deeper the water, the more pressure is exerted

Question 22

Dam

Answer 22

-base of dam is thicker then its top
- water pressure at the bottom is higher

Question 23

sucking on a straw

Answer 23

• lower the air pressure inside as we remove some air inside
• causes higher atmospheric pressure outside the straw to push liquid up the straw

Question 24

pressing a suction cup on the wall

Answer 24

• air between the surface of wall and cup is removed
• allows high atmospheric pressure to push it firmly on the surface of the wall

Question 25

work done

Answer 25

- transfer of energy - from object to object - one form of energy to another - force applied on an object -causes it to travel a dist in the same direction of force

Question 26

S.I unit for work done

Answer 26

joule

Question 27

formula for work done

Answer 27

work = force (N) X dist (M)

Question 28

when is work NOT done

Answer 28

- if object does NOT move when a force act on it - NO transfer of energy

Question 29

Law of conservation of energy

Answer 29

energy is CANNOT be created OR destroyed - total amt of energy before is the same as after the process

Question 30

Biofuels

Answer 30

- made from animal waste or plant materials that CANT be eaten - power vehicles that produce CO2 - CO2 taken in by plants

Question 31

formula of biofuels

Answer 31

CPE (biofuel) ---- H.E -----KE (vehicles)

Question 32

fossil fuels

Answer 32

- remains of dead living things - limited - not recommended

Question 33

formula of fossils fuels

Answer 33

- CPE (fossil fuel) ----H.E ---- K.E (turbine) ----E.E (generator)

Question 34

impact of fossils fuels

Answer 34

- burning of fossil fuels release air pollutants and greenhouse gases - causing climate change

Question 35

solar energy

Answer 35

- solar panels capture sunlight - does not release air pollutants

Question 36

formula of solar energy

Answer 36

L.E (sun) ------E.E (solar cell)

Question 37

hydroelectric energy

Answer 37

- a hydroelectric power station stores water behind the dam - when water is releases, moving water powers the turbines to generate electricity

Question 38

formula of hydroelectric energy

Answer 38

GPE (water behind dam) ----- KE (moving water) ---- KE (turbine) ---- E.E (generator)

Question 39

impact of hydroelectric energy

Answer 39

- kills plants and forces animals to move

Question 40

wind energy

Answer 40

KE (wind) ----- KE (wind turbine) --- E.E (generator)

Question 41

impact of wind energy

Answer 41

- large plots of land need to be cleared - birds killed if they collide into the blades

Question 42

geothermal energy

Answer 42

- heat stored in earth core - used steam to generate electricity

Question 43

formula of geothermal electricity

Answer 43

- HE (earth core) -- KE (steam) --- KE (turbine) --- EE (generator)

Question 44

cons of geothermal energy

Answer 44

- large lands cleared

Question 45

nuclear energy

Answer 45

- nucleus of atoms - obtained through nuclear reactions - when a heavy atom splits into smaller atoms, a large amt of HE is released

Question 46

formula of nuclear energy

Answer 46

nuclear energy (atoms) --- HE ---KE (turbine) ---EE (generator)