Physics paper 2 forces and motion

Question 1

average speed (m/s)=

Answer 1

distance/time

Question 2

acceleration(m/s^2)

Answer 2

change in velocity/time taken

Question 3

distance time graph what do each sections mean?

Answer 3

1) gradient=speed
2) flat=stopped
3) downhill- going back towards starting point
4) curves= acceleration or deceleration

Question 4

v-t graphs?

Answer 4

1) gradient=acceleration
2) flat=steady speed
3) downhill= deceleration
4) area under curve=distance
5) curve = changing acceleration

Question 5

what is gravity?

Answer 5

the force of attraction between all masses

Question 6

what force keeps planets, moons and satellites in their orbits?

Answer 6

gravitational force

Question 7

what is the orbit a balance between?

Answer 7

the forward motion of the object and the force of gravity pulling it inwards

Question 8

what is force measured in?

Answer 8

Newtons using a spring balance or newton meter

Question 9

what is mass measured in

Answer 9

kilograms using a mass balance

Question 10

weight=

Answer 10

mass x gravitational field strength (W= m x g)

Question 11

give 7 types of force

Answer 11

1) gravity/weight acting straight downwards
2) reaction force from a surface acting upwards
3) electrostatic force- between 2 charged objects
4) thrust-push or pull due to engine speeding it up
5) drag/air resistance/friction slowing things down
6) lift due to an aeroplane wing
7) tension in a rope or cable

Question 12

what are 3 types of friction?

Answer 12

1) between solid surfaces which are gripping
2) between solid surfaces which are sliding past each other
3) resistance or drag from fluids (liquids or gases)

Question 13

how do you reduce friction between solid surfaces sliding past each other?

Answer 13

using a lubricant like oil or grease- friction between solids can often cause wear of the two solids in contact

Question 14

how do you reduce resistance from fluids?

Answer 14

make the shape of object streamlined- lorries and caravans have deflectors on them to make them more streamlined

Question 15

in a fluid what increases when speed increases?

Answer 15

friction

Question 16

investigation motion of a toy car experiment-average speed

Answer 16

1) mark a line on the ramp for car to start each time
2) measure distance between each light gate
3) let go of car just before light gate
4) light gate connected to computer so when car passes a beam of light is broken and a time is recorded by date-logging software
5) repeat this experiment to get an average time-reliable
6) using times and distance you can find the cars average speed

Question 17

what 5 things could you change to investigate the factors that affect the cars motion?

Answer 17

1) changing mass
2) friction-different materials on ramp
3) acceleration-start car higher up on ramp
4) change the angle of the ramp
5) try different cars-size,shape, weight

Question 18

what is free fall?

Answer 18

when an object is falling with no driving force acting on it

Question 19

what is in balance in terminal velocity?

Answer 19

resistance=weight

Question 20

how to investigate free fall

Answer 20

using sycamore seeds-small weight and large surface area-reach t.v quickly

1) collect bunch of seeds of diff sizes and measure the mass and wing length of each one. repeat each measurement to make sure it’s accurate using ruler. use all the seeds with similar mass but different wing lengths
2) drop each seed from same height and use stopwatch to find how long each one takes to fall to the ground-higher you drop the better-larger measurement and so improves accuracy
3) repeat experiment
4) plot graph-shows bigger wings-larger SA so higher drag. higher drag means lower terminal velocity so slower free fall

Question 21

what is Newton’s first law of motion?

Answer 21

Balanced forces mean no change in velocity

Question 22

what is Newton’s 2nd law of motion?

Answer 22

a resultant force means acceleration- if unbalanced force, the the object will accelerate in that direction

Question 23

the bigger the force..

Answer 23

the greater the acceleration/deceleration

Question 24

the bigger the mass..

Answer 24

the smaller the acceleration

Question 25

the unbalanced force is called ?

Answer 25

the resultant force

Question 26

force=

Answer 26

mass x acceleration (F=ma)

Question 27

what affects your stopping distance?

Answer 27

thinking distance and braking distance

Question 28

what affects thinking distance?

Answer 28

1) speed | 2) how dopey you are- tiredness,drugs,alcohol,old age, inexperience

Question 29

what affects braking distance?

Answer 29

1) speed 2) mass of vehicle 3) brake conditions 4) grip-road surfaces/weather conditions/ tyres

Question 30

what is a moment?

Answer 30

the turning effect of a force

Question 31

moment is measured in?

Answer 31

Nm

Question 32

moment=

Answer 32

force (N) x perpendicular DISTANCE(m) between line of action and pivot

Question 33

how do you get the maximum moment?

Answer 33

by pushing at right angles(perpendicular) to the pivot because this is longest distance between the line of action and the pivot

Question 34

what is the point through which the weight of a body acts

Answer 34

the centre of gravity

Question 35

a freely suspended object will swing until when?

Answer 35

the centre of gravity is vertically below the point of suspension

Question 36

how can you find the centre of gravity of a shape

Answer 36

1) suspend the shape and a plumb line from the same point 2) draw a line along the plumb line 3) do the same thing again, but suspend the shape from a different pivot point 4) the centre of gravity is where your two lines cross

Question 37

what does Hooke's law say?

Answer 37

that extension is proportional to force

Question 38

what is the length of an unstretched metal wire called?

Answer 38

its natural length

Question 39

when does Hooke's law stop working?

Answer 39

when the force is great enough and has reached its elastic limit-if you increase force past this point the material will be permanently stretched

Question 40

what material displays elastic behaviour?

Answer 40

when it returns to its original shape once all the forces are removed

Question 41

what is a galaxy?

Answer 41

a large collection of stars

Question 42

what is the universe?

Answer 42

a large collection of billions of galaxies

Question 43

if an object is travelling in circles what happens to its direction?

Answer 43

its constantly changing

Question 44

how do planets move around the Sun?

Answer 44

in almost circular orbits-slightly elliptical

Question 45

what are comets?

Answer 45

small lumps of icy rock which orbit the Sun

Question 46

what type of orbit to comets have?

Answer 46

very elliptical with the Sun at one focus

Question 47

what are comets periods in relation to Earth?

Answer 47

much longer because they travel from the outer edges of the Solar System

Question 48

why do comets travel faster when nearer the Sun?

Answer 48

because the increased pull of gravity makes it speed up closer to the Sun

Question 49

what are the artificial satellites called that have an orbital period of exactly one day?

Answer 49

geostationary satellites

Question 50

orbital speed=

Answer 50

2 x pii x orbital radius/ time period

Question 51

What's Newton's third law of motion?

Answer 51

Reaction forces: If object A exerts a force on object B then object B exerts the exact opposite force on object A

Question 52

What do vector quantities have?

Answer 52

Size and direction

Question 53

What are some vectors?

Answer 53

Force, velocity, displacement, acceleration, momentum

Question 54

What are scalar physical qualities?

Answer 54

Have size but not direction

Question 55

What are some examples of scalar quantities?

Answer 55

Mass, temperature, time, length

Question 56

What is the resultant force?

Answer 56

Resultant forces refers to the reduction of a system of forces acting on a body to a single force.

Question 57

How do you work out the resultant force?

Answer 57

choose a direction as the positive e.g north. Add any forces in the north direction and subtract any forces in the south direction

Question 58

Momentum is measured in?

Answer 58

Kgm/s

Question 59

Momentum =

Answer 59

Mass(kg) x velocity (m/s)

Question 60

Momentum before=

Answer 60

Momentum after

Question 61

When two objects collide, how do you find the velocity after the collision?

Answer 61

1- choose a positive direction e.g right 2- find total momentum before collision so momentum of object A + momentum of object B 3- find total momentum after collision - add the object masses x velocity 4- addition of object masses x velocity = total momentum before so rearrange to find v

Question 62

What do forces cause?

Answer 62

Changes in momentum

Question 63

What does a larger force do to the momentum?

Answer 63

Means a faster change in momentum and great acceleration

Question 64

Why do cars have crumple zones?

Answer 64

Crumple on impact, increasing he time taken for the car to stop

Question 65

What do cars have seat belts?

Answer 65

They stretch slightly, increasing the time taken for the wearer to stop reducing the forces acting on the chest

Question 66

Why are airbags used?

Answer 66

Slow you down more gradually

Question 67

Is someone's momentum changes very quickly what happens to the force?

Answer 67

The forces on the body will be very large and more likely to cause injury

Question 68

How are cars designed

Answer 68

To slow people down over a longer time when they have a crash- the longer it takes for a change in momentum, the smaller the force and so less severe the injuries

Question 69

Force acting (N) =

Answer 69

Change in momentum (kgm/s) / time taken for change to happen (s)

Question 70

Total anticlockwise moments =

Answer 70

Total clockwise moments

Question 71

When total anticlockwise moments don't equal the total clockwise moments, what will there be?

Answer 71

A resultant force