Topic 5 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a vector quantity

+ examples

A

Has a magnitude and a direction

Force ,velocity , displacement , acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a scalar quantity

+examples

A

Has only magnitude no direction

Speed ,distance, mass , temperature , time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Examples of contact forces

A

Friction , air resistance , tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Examples of non contact forces

A

Magnetic force , gravitational force , electrostatic force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are gravity’s important effects

A

Gives everything a weight

Makes things fall toward the ground

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is weight

A

The force acting on an object due to gravity

Measure in newtons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a resultant force

A

The overall force acting on an object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens when a force moves an object through a distance

A

Work is done and energy is transferred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How to we draw a scale diagram of forces in equilibrium

A

The tip of the last force you draw should end at the tail of the first force you drew begins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the equation force = ke also work for

A

Compression - the extension is the difference between the natural and compressed lengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the limit of proportionality

A

The Max force that a spring can take before extension is no longer directly proportional to force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Investigating springs practical

A
  1. Measure natural length of spring with ruler clamped to stand - take reading at eye level (add a marker eg tape) to the bottom of the spring to make it more accurate
  2. Add mass to spring and allow it to come to rest
  3. Record the mass and the new length of the spring - record the extension (change in length)
  4. Repeat until you have enough measurements (6+)
  5. Plot on a graph - it will curve when the limit of proportionality is exceeded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a moment

A

The turning effect of a force

To get the max moment you must push at right angles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do levers do

A

Increase the distance form the pivot so less force is needed to get the same moment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Examples of levers

A

Long stick , wheelbarrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are gears

A

Circular disks with teeth that interlock with other gears.

They are used to transmit rotational force

Larger - bigger moment, slower
Smaller - smaller moment , faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is upthrust

A

The resultant force cause by different amounts of pressure acting on different parts of a submerged object

It is equal to the weight of fluid that has been displaced by an object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

When/how does an object float

A

When upthrust = the objects weight

Whether or not an object will float depends on density

Less dense(than fluid) - floats
More dense (than fluid)- doesn’t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the atmosphere

A

A thin layer of air that surrounds the earth (thin compared to size of earth)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is atmospheric pressure

A

Created on a surface by air molecules colliding with the surface

21
Q

What happened to atmospheric pressure as height increases

A

It decreases as the atmosphere become less dense so less air molecules can collide with surfaces

22
Q

Distance vs displacement

A

Distance = how far an object moves

Displacement = distance and direction in a straight line from the starting point

23
Q

What are the everyday speeds In m/s

A

Walking - 1.5
Running - 3
Cycling - 6
Car - 25
Train - 55
Plane - 250

24
Q

What is acceleration

A

Change in velocity over a certain amount of time

25
Q

What is the speed of sound and light in m/s

A

Sound - 330
Light - 300,000,000

26
Q

What is the constant acceleration (uniform acceleration) of an object in free fall

A

9.8 m/s squared

27
Q

What does the gradient of a velocity time graph give you

A

Acceleration

28
Q

What does the area under a velocity time graph give you

A

The distance travelled

29
Q

What do curves represent on a distance time graph

A

Acceleration and deceleration

30
Q

What is friction drag and air resistance

A

Friction - acts in opposite direction to movement ,slows object down

Drag - friction through a fluid

Air resistance - type of drag but with air particles

31
Q

Correlation between drag and speed

A

As speed increases drag increases

32
Q

What happens to an object as it falls through a fluid

A

Quickly reaches a max speed (terminal velocity) due to gravity being greater than friction force

Acceleration gradually reduces and object falls at steady speed

33
Q

What does terminal velocity depend on

A

Air resistance

34
Q

What is Newton’s first law

A

If the resultant force on a stationary object is zero the object will remain stationary. If the resultant force on a moving object is zero it’ll just carry on moving at the same velocity

35
Q

Newton’s second law

A

States that acceleration is directly proportional to the resultant force

36
Q

Newtown third law

A

When two objects interact the forces they produce are equal and opposite

37
Q

What is inertia

A

An objects tendency to continue the same state of motion when acted on by a resultant force

Inertial mass is calculated by f=ma (newtons second law)

38
Q

Investigating motion practical
- tests Newton’s second law

A

1.set up trolley that holds a piece of card that will interrupt the signal from a light gate. The light gate will measure the velocity

  1. Connect the trolley to string that goes over a pulley and is connect to a hook with mass on

3.the weight of the hook will provide an acceleration force

  1. Mark the starting line on the table the trolley is on
  2. Place the trolley on the line and hold it in place - now hook masses onto the hook - let the hook hang so it is not loose and touching the table
  3. Release the trolley and record the acceleration measure by the light gate
  4. Repeat this twice to get an average acceleration
39
Q

Varying mass and force - practical extension.

A

To investigate the effect of mass add masses to the trolley instead of the hook

To investigate the effect of force add the masses from the trolley to the hook one at a time with each repetition of the experiment

40
Q

How can Newton’s second law explain the results of the varying mass and force practical

A

By adding masses to the trolley the mass of the whole system increases but the force status the same

By transferring masses from the trolley to the Hook the force increases but mass of the system doesn’t

41
Q

What affects thinking distance

A

Speed , reaction time
Tiredness , drugs , alcohol, distractions.

42
Q

What affects braking distance

A

Speed, weather , tyre conditions , how good your brakes are

43
Q

Reaction time practical

A
  1. Sit with arm resting on edge of table - someone holds a ruler so it hangs between your thumb and forefinger
  2. Ruler drop without warning - you must catch the ruler as fast as possible
  3. Take a measurement at the point the ruler was caught
  4. Repeat with the same person and calculate mean

5 a blob of clay can be used at bottom of ruler to stop it waving

6 use the same ruler and same person dropping it

7 factors of reaction time can be measure eg playing music as a distraction

44
Q

How does braking work

A

When the brake pedal is pushed the brake pads press onto the wheels which causes friction.
Kinetic -> thermal

45
Q

What does speed affect in a car

A

Braking distance

46
Q

What happens to momentum in a closed system

A

The total momentum before = total momentum after

  • momentum is conserved
47
Q

How calculate the velocity of forces which interact with one another

A

Momentum for = momentum after

As momentum = mass x velocity

48
Q

If momentum large changes fast on a person what can occur

A

Injury

49
Q

What can help reduce forces acting upon someone by momentum

A

Crumple zones
Seatbelt
Airbag
Helmet
Crash mat