Topic 8 - Kinematics

Question 1

scalar quantity

Answer 1

a quantity with magnitude but no direction

Question 2

vector quantity

Answer 2

a quantity with magnitude AND direction

Question 3

distance

Answer 3

• scalar quantity
• how far an object has moved

Question 4

displacement

Answer 4

• vector quantity
• distance and direction in a straight line from starting point to finishing point of an object ( with bearing )

Question 5

speed

Answer 5

• scalar quantity
• how fast an object is moving with no regard to direction

Question 6

velocity

Answer 6

• vector quantity
• how fast an object is moving and in which direction ( bearing )

Question 7

speed equation

Answer 7

speed = distance / time

Question 8

moving in a circle

Answer 8

• constant speed while the velocity is constantly changing as…
• velocity is a vector with both magnitude and direction
• constantly changing direction

Question 9

walking typical speed

Answer 9

1.5 m/s

Question 10

running and cycling typical speed

Answer 10

running : double walking
cycling : double running

Question 11

acceleration equation

Answer 11

change in velocity / time
v - u / t

Question 12

distance - time graphs

Answer 12

• gradient = speed
• straight uphill sections = steady speed
• straight line = stationary
• steep curved section = accelerating
• leveling curve = decelerating

Question 13

velocity - time graphs

Answer 13

• gradient = acceleration
• straight line = constant speed
• steeper = greater ac/deceleration

Question 14

what is a resultant force?

Answer 14

the resultant force has the same effect as all the individual force acting on the object in a straight line

Question 15

what is a force

Answer 15

• a vector quantity
• a push or pull that acts on an object due to an interaction with another object

Question 16

contact forces acting on a body

Answer 16

• forwards thrust
• driving force
• friction
• air resistance (opposite direction)
• normal contact force from the ground acts upwards

Question 17

non contact forces

Answer 17

• weight caused by gravitational force acts downwards
• electrostatic force
• magnetic force

Question 18

Newton’s First Law

Answer 18

if the r.f on an object is zero then it will continue moving at the same velocity
- if it is stationary it will remain stationary

Question 19

Newton’s Second Law

Answer 19

• an object’s acceleration is directly proportional to its resultant force
  F = ma

Question 20

inertia

Answer 20

an object’s tendency to continue moving at same velocity

Question 21

inertial mass

Answer 21

how difficult it is to change velocity of an object
F/ a

Question 22

Newton’s Third Law

Answer 22

• when two objects interact, the forces they exert on each other are equal and opposite

Question 23

what is friction? how is it affected by speed

Answer 23

frictional forces act in the opposite direction of movement
- as speed of an object increases the frictional forces also increase

Question 24

what are most of the resistive forces caused by?

Answer 24

air resistance or drag

Question 25

how does a falling object reach terminal velocity?

Answer 25

• when a falling object first sets off,
• the force of gravity is much greater than the frictional air resistance pushing upwards.
• object accelerates downwards

Question 26

how does a falling object reach terminal velocity? (P2)

Answer 26

• with increasing speed, the air resistance also increases, reducing acceleration
• eventually, the air resistance pushing upwards equals the force of gravity pushing downwards
• it will reach its terminal velocity, stay at same speed and stop accelerating

Question 27

gravity

Answer 27

the force that makes objects with mass attract to each other
it makes all things accelerate towards the ground

Question 28

weight

Answer 28

the force acting on an object due to gravity

Question 29

weight equation

Answer 29

W= mg

Question 30

work done

Answer 30

work done = force x distance

Question 31

how does a moving object heat up?

Answer 31

• when an object moves it does work against friction
• some energy is transferred by heating to thermal energy stores of object
• and away from KE of object
• overall temp of object and surface increase

Question 32

stopping distance

Answer 32

distance covered in the time between a driver spotting a hazard and the vehicle coming to complete stop

Question 33

stopping distance equation

Answer 33

thinking distance + braking distance

Question 34

thinking distance

Answer 34

distance the vehicle travels during the time between the driver seeing a hazard and applying the breaks

Question 35

braking distance

Answer 35

distance the vehicle travels after braking force is applied

Question 36

why do objects fall at a slower rate on the Moon than the earth?

Answer 36

• moon’s g.f.s is much lower
• the weight of object is much lower on moon than earth
• gravity causes objects to accelerate towards the ground : objects accelerate slower on moon

Question 37

what factors affect the strength of gravitational field?

Answer 37

the closer you are to the centre of mass causing the gravitational field, the stronger it is

Question 38

factors affecting thinking distance

Answer 38

• vehicle speed
• reaction time which is affected by drugs, alcohol or tiredness

Question 39

factors affecting braking distance

Answer 39

• vehicle speed
• brake condition
• tyre condition
• road condition

Question 40

how does speed affect thinking distance

Answer 40

• thinking distance is directly proportional to speed

Question 41

how does speed affect braking distance

Answer 41

• braking distance increases by a scale factor of speed increase
• 1/2mv2

Question 42

car safety : seatbelts

Answer 42

• stretches slightly and prevents component from exiting vehicle in crash

Question 43

car safety : air bags

Answer 43

increase collision time for head and chest

Question 44

3 SUVAT equations

Answer 44

v2 = u2 + 2as
v = u + at
s = ut + 1/2 at