P5 Forces Flashcards

1
Q

What is force?

A

Vector quantity (have a magnitude and a direction)

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2
Q

Examples of physical quantities that are vector quantities

A

-Force, velocity, displacement, acceleration, momentum

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3
Q

Examples of physical quantities that only have magnitude and no direction

A

Scalar quantities: Speed, distance, mass, temperature, time

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4
Q

What usually represents a vector?

A
  • An arrow
  • The length shows the magnitude
  • The direction shows the direction of the quantity
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5
Q

Contact force

A

Forces that make contact (e.g. pushing something)

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6
Q

Non contact force

A

Forces that don’t make contact (magnetic force, gravitational force)

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7
Q

What is gravitational force?

A

The force of attraction between masses

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8
Q

Mass

A

The amount of ‘stuff’ in an object

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9
Q

Weight

A

The force acting on an object due to gravity

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10
Q

What affects weight?

A

The strength of the gravitational field at the location of the object

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11
Q

Centre of mass

A

A point at which you assume the whole mass is concentrated

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12
Q

How is weight measured?

A

A calibrated spring balance

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13
Q

Are mass and weight directly proportional?

A

Yes

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14
Q

Weight (N) = ?

A

Mass (kg) * GFS (N/kg)

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15
Q

What is resultant force?

A

The overall force on a point or object

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16
Q

What are parallel forces?

A

The forces are all along the same line (you can add and subtract the forces to find the resultant force)

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17
Q

What is work done in terms of distance and force?

A

When a force moves an object through a distance, energy is transferred and work is done on the obejct

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18
Q

Work done eq (force and distance)

A

Force * Distance

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19
Q

What happens when the resultant force is 0?

A

The object is equilibrium (the 3 forces will make a triangle)

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20
Q

Why should we split forces into simpler components?

A

Because some forces are at difficult angles to work with

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21
Q

Distance

A

How far an object has moved (scalar quantity)

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22
Q

Displacement

A

A vector quantity which measures the distance in a straight line from an object’s starting point to finishing point

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23
Q

Speed

A

How fast you are going

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24
Q

Velocity

A

The speed in a given direction

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25
Q

distance travelled eq (speed and time)

A

Distance = speed / time

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26
Q

Walking speed

A

1.5 m/s

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27
Q

Running speed

A

3 m/s

28
Q

Cycling speed

A

6 m/s

29
Q

Car speed

A

25 m/s

30
Q

Train speed

A

30 m/s

31
Q

Plane speed

A

250 m/s

32
Q

Acceleration

A

The change in speed in a certain amount of time

33
Q

Deceleration

A

Negative acceleration

34
Q

Uniform acceleration

A

The constant accelertaion

35
Q

uniform acceleration equation

A

v^2 - u^2 = 2as

36
Q

How to work out speed in distance time graphs

A

Gradient

37
Q

Flat parts on distance time graphs

A

Stationary

38
Q

Straight parts on distance time graphs

A

Steady speed

39
Q

Curves on distance time graphs

A

Represent acceleration and deceleration

40
Q

Steepening on distance time graphs

A

Speeding up

41
Q

Levelling off on distance time graphs

A

Slowing down

42
Q

Velocity time graph

A

Shows how an object’s velocity changes as it travels

43
Q

Gradient on velocity time graph

A

Acceleration

44
Q

Flat sections on velocity time graph

A

Travelling at a steady speed

45
Q

Steeper the gradient on velocity time graphs

A

The greater the acceleration or deceleration

46
Q

Uphill sections on velocity time graphs

A

Acceleration

47
Q

Downhill sections on velocity time graphs

A

Deceleration

48
Q

How to work out distance travelled in a time interval in a velocity time graph

A

The area

49
Q

Friction

A

The opposite force in direction to movement

50
Q

How to reduce friction

A

Use a lubricant

51
Q

Drag

A

The resistance you get in a fluid (gas or liquid)

52
Q

Example of drag

A

Air resistance

53
Q

What can be done to reduce drag

A

Keeping the shape of the object streamline

54
Q

Examples of objects that increase drag

A

Parachutes

55
Q

Terminal velocity

A

When an object has reached its maximum speed and will fall at a steady speed

56
Q

Why is there terminal velocity?

A
  • Force of gravity is much more than frictional force, therefore the object accelerates
  • As the speed increases, friction builds up
  • This gradually reduces the acceleration until eventually the friction force is zero
57
Q

What usually affects terminal velocity

A
  • The shape and area of the object

- Objects with large surface areas have lower terminal velocities

58
Q

Newton’s first law

A
  • If the resultant force on a stationary object is zero, the objects will remain stationary.
  • If the resultant force on a moving object is zero, it’ll just carry on moving at the same velocity
59
Q

Newtons second law

A

Newton’s second law states that the acceleration of an object depends upon two variables – the net force acting on the object and the mass of the object.

60
Q

Resultant force eq (acceleration and mass)

A

f = m*a

61
Q

Inertia mass

A

Measures how difficult it is to change the velocity of an object

62
Q

Inertia mass on newton’s second law

A

The mass (m = f/a)

63
Q

Newton’s third law

A

When 2 objects interact, the forces they exert on each other are equal and opposite

64
Q

Momentum

A

A vector quantity resultant from mass and velocity

65
Q

Momentum equation

A

mass (kg) * velocity (m/s)

66
Q

Conservation of momentum

A

The total momentum before the event is the same as after the event in a closed system