Unit 1

Question 1

what is speed

Answer 1

the distance traveled per unit time( speed = distance/time)

Question 2

what is acceleration

Answer 2

when the speed is changing(Change in velocity over time)

Question 3

what is velocity

Answer 3

speed in a given direction

Question 4

what is mass

Answer 4

the amount of matter in an object

Question 5

what is weight

Answer 5

it is a gravitational force measured in newtons

Question 6

how do you calculate weight

Answer 6

mass x gravitational field strength

Question 7

what will the effect be in the same object on different planets

Answer 7

mass will be the same but weight will be different

Question 8

what is density

Answer 8

mass/unit volume

Question 9

how do you find the density of a liquid

Answer 9

by measuring the mass of a measuring cylinder, adding the liquid and measuring the mass again
The mass of the liquid can then be found along with density

Question 10

how to find the density of irregular shaped object

Answer 10

by placing it in water and measuring the volume before and after

Question 11

what is the density of water

Answer 11

1 g/cm^3

Question 12

what happens if the density of the object is greater or less than the density of water

Answer 12

if greater, it will sink
if lesser, it will float

Question 13

What is newtons first law

Answer 13

states that an object has constant velocity unless acted on by a resultant force

Question 14

what is newtons second law

Answer 14

force x mass = acceleration (f=ma)

Question 15

what is newtons third law

Answer 15

every action force has an equal and opposite reaction

Question 16

what is terminal velocity

Answer 16

the maximum velocity reached in free fall

Question 17

how does terminal velocity get reached

Answer 17

as objects accelerate , air resistance increases
This causes resultant force downwards to decrease
acceleration starts to decrease
there is then equal and opposite reaction so there is no resultant force
terminal velocity is reached

Question 18

What is friction

Answer 18

the force between two surfaces which impedes motion and results in heating

Question 19

features of an object moving in a circle

Answer 19

speed is constant but direction is always changing
means velocity is always changing
it is therefore accelerating and there must be a force perpendicular to its velocity towards the centre of the circle

Question 20

what is elastic deformation

Answer 20

the object returns to its original shape when the load has been removed

Question 21

what is plastic deformation

Answer 21

object does not return to original shape

Question 22

what is hookes law

Answer 22

Force = spring constant x spring extension (force = kx)

Question 23

what is the limit of proportioanality

Answer 23

where the force extension graph stops being linear
from then on the spring doesnt obey hookes law and leads to plastic deformation

Question 24

what is the moment of a force

Answer 24

the measure of its turning effect
moment of a force = force x perpendicular distance

Question 25

in terms of turning effect, what is the pivot point

Answer 25

the point which the object can rotate about

Question 26

what happens if the force is applied in the same lines of the pivot(Turning effects)

Answer 26

the object will remain stationary

Question 27

what is the principle of moments

Answer 27

when the sum of clockwise moments equals the sum of anti clockwise moments

Question 28

what is the centre of mass

Answer 28

the point which all mass can be considered to act

Question 29

what happens if the centre of mass is below the point of suspension of an object

Answer 29

it will be in stable equilibrium example: hanging plant pot

Question 30

what happens if the centre of mass is higher than the point of the suspension

Answer 30

it will be in unstable equilibrium

Question 31

what is a vector

Answer 31

force with magnitude and direction

Question 32

what is a scalar quantity

Answer 32

force with just magnitude

Question 33

what is momentum

Answer 33

mass x velocity

Question 34

what is impulse

Answer 34

force x time also change in momentum

Question 35

what is the principle of conservation of momentum

Answer 35

the total momentum before is equal to the total momentum afterwards

Question 36

what is an inelastic collision and formula

Answer 36

when kinetic energy is lost initial momentum (first object) + initial momentum (2nd object) = (1st mass + 2nd mass) final velocity of both objects

Question 37

what is an elastic collision and formula

Answer 37

when kinetic energy is the same before and after initial momentum (1st object) + initial momentum (2nd object) = final momentum (1st object) + final momentum (2nd object)

Question 38

what is kinetic energy

Answer 38

1/2 mv^2

Question 39

what is gravitational potential energy

Answer 39

mgh(mass x gravity x height)

Question 40

how is gravitational potential energy and kinetic energy related

Answer 40

kinetic energy = gravitational potential energy

Question 41

what is work

Answer 41

when a force moves something through a distance work done is equal to energy transferred (force x distance)

Question 42

what is power

Answer 42

the rate at which energy is transferred or rate at which work is done power = energy transferred/time

Question 43

what is efficiency

Answer 43

the ratio of useful work done to the total energy supplied efficiency = useful energy output/total energy input

Question 44

what is renewable energy

Answer 44

energy which can be replenished as quickly as its used examples: wind, geothermal, tidal, solar ,water waves

Question 45

which energy sources do not require the sun as the original source

Answer 45

geothermal, nuclear and tidal

Question 46

why is non renewable energy used

Answer 46

has large energy output and usually cheaper

Question 47

what is pressure

Answer 47

force/area measures in pascals

Question 48

how to calculate liquid pressure

Answer 48

density x gravity x height