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Physics > Topic 2 - Motion and forces > Flashcards

Topic 2 - Motion and forces Flashcards

1
Q

What is the main difference between scalar and vector quantities?

A

Scalar quantities - size but no direction

Vector quanitites - size and direction

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2
Q

Give 6 examples of vector quantities

A 
1- force 
2- velocity
3- displacement
4- weight
5- acceleration
6- momentum
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3
Q

Give 6 examples of scalar quantities

A
  1. Speed
  2. Distance
  3. Mass
  4. energy
  5. Temperature
  6. Time
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4
Q

Define velocity

A

Speed in a given direction

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5
Q
  1. a) Whats the formula to work out speed?

b) - rearrange the formula to work out distance

A

a) speed = distance/time

b) distance = speed * time

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6
Q

A curve on a distance-time graph represents…

A

acceleration

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7
Q

On a distance-time graph, the gradient at any point gives is the…

A

speed of the object

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8
Q

Whats the 1st formula to work out acceleration?

A

a= v-u/t

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9
Q

Whats the 2nd formula to work out acceleration?

A

v squared - u squared = 2ax

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10
Q

On a velocity time graph, the gradient is equal to…

A

acceleration

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11
Q

On a velocity-time graph, a curve means…

A

changing acceleration

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12
Q

What does the area under a velocity-time graph tell us?

A

The distance travelled

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13
Q

What is the typical speed of walking?

A

1.4 m/s

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14
Q

What is the typical speed of running?

A

3 m/s

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15
Q

What is the typical speed of cycling?

A

5.5 m/s

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16
Q

What is the typical speed of wind?

A

5 - 20 m/s

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17
Q

What is the typical speed of sound in air?

A

340 m/s

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18
Q

What is the typical speed of cars in a built-up area?

A

13 m/s

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19
Q

What is the typical speed of cars on a motorway?

A

31 m/s

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20
Q

What is the typical speed of trains?

A

up to 55 m/s

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21
Q

Acceleration for objects in free fall is …. (the same as the value for gravitational field strength)

A

10 m/s squared

22
Q

(Newtons first law - part 1)

If the resultant force on a stationary object is zero, it will remain …..

A

stationary

23
Q

(Newtons first law - Part 2)

If the resultant force on a moving object is zero, itll just carry on moving at the ……

A

same velocity

24
Q

What is newtons second law and what is the equation that shows this?

A

Acceleration is proportional to the resultant force

f = ma

25
Q

Define ‘weight’ and recall the equation to work out weight?

A

The force acting on an object due to gravity

w= m*g

26
Q

How is weight measured?

A

using a newtonmeter

27
Q

If the gravitational field strength changed, that means the weight of an object would ….

(change?/stay the same?)

A

change

28
Q

In the trolley experiment, what is the reason that the trolley accelerates

A

The force caused by the hanging mass attached to the trolley causes it to accelerate

29
Q

Why is a length of card placed on the trolley?

A

To interrupt the light gate beams. which will be measuring the speed of the trolley

30
Q

If an object travelling in a circle is constantly changing velocity, what does this tell us?

A

The objects accelerating

31
Q

What is the resultant force called that keeps something moving in a circle?

A

The centripetal force

32
Q

What does inertial mass measure and how can we work it out?

A

How difficult it is to change the velocity of an object

m = f/a (rearranged formula f= ma)

33
Q

What is Newtons third law?

A

When two objects interact, the forced they exert on each other are equal and opposite

34
Q

How can newtons third law be applied in an equilibrium situation?

A

For a book on a desk, the pair of forces due to Newtons third law is:

  1. The book is pulled down its weight due to gravity
    - the book pulls back up on the earth
  2. The normal contact force from the table pushing up on a book and the normal contact force from the book pushing down on the table
35
Q

Newtons third law explains the conservation of ….

A

momentum

36
Q

What is the formula to work out momentum?

A

p = mv

37
Q

Use a collision between a white and red ball to describe the conservation of momentum?

A

1- Before the collision, the white ball would be moving with a velocity so it has a momentum above 0, but the red ball has no velocity
2- After the collison, The red ball now has collision but the white ball would be moving slower and so it would have a smaller momentum.
3. The combined momentum of the red and white ball after the collision is equal to the momentum of the white ball before the collision

38
Q

What is the formula that relates force, and momentum

A

force = final momentum - initial momentum / time

39
Q

Define acceleration?

A

change in velocity in a given time

40
Q

What are two ways of testing reaction times?

A
  1. Computer-based tests

2. Ruler drop test

41
Q

What can you do to make the rule drop test a fair test?

A
  1. Have a third person to be at eye level with the ruler
  2. Repeat experiment a lot of times and find average
  3. Keep other variables the same (use same ruler for each repeat and have the same person dropping it)
42
Q

Stopping distance =….

A

thinking distance + braking distance

43
Q

What is thinking distance affected by? (2 factors)

A
  1. Your reaction time

2. Your speed

44
Q

What is braking distance affected by? (4 factors)

A
  1. Your speed
  2. Mass of car
  3. Condition of the brakes
  4. How much friction there is between your tyres and the road
45
Q

What can affect reaction time?

A

Tiredness, alcohol, drugs or distractions

46
Q

Why can large decelerations be dangerous?

A

They require a large force

47
Q

How can large decelerations in cars be prevented?

A

by slowing the car down over a long period of time

48
Q

the brakes of a car do work on the cars wheels, so when the car stops:

energy in the car’s kinetic energy store = work done by the brakes

Explain this equation

A

To stop a car, the brakes must transfer ALL of its kinetic energy

49
Q

Define thinking distance?

A

The distance a car travels during the drivers reaction time

50
Q

Define braking distance?

A

The distance taken to stop once the brakes have been applied

Physics (13 decks)

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