5. Forces Flashcards

1
Q

What is a scalar?

A

Quantities that are fully described by magnitude or size

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2
Q

What are vectors?

A

Quantities that are fully described by both a magnitude and direction

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3
Q

What is distance?

A

A scalar quantity that refers to ‘how much ground an object has covered’

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4
Q

What is displacement?

A

A vector quantity that refers to ‘how far out of place an object is’

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5
Q

What is magnitude?

A

Size

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6
Q

How can vectors be drawn?

A

Using arrows

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7
Q

Is time a vector or scalar quantity?

A

scalar

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8
Q

Is force a vector or scalar quantity?

A

Vector

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9
Q

Is friction a vector or scalar quantity?

A

Vector

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10
Q

Is weight a vector or scalar quantity?

A

Vector

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11
Q

Is displacement a vector or scalar quantity?

A

Vector

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12
Q

Is distance a vector or scalar quantity?

A

Scalar

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13
Q

Is density a vector or scalar quantity?

A

Scalar

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14
Q

Is energy a vector or scalar quantity?

A

Scalar

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15
Q

Is frequency a vector or scalar quantity?

A

Scalar

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16
Q

Is mass a vector or scalar quantity?

A

Scalar

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17
Q

Is power a vector or scalar quantity?

A

Scalar

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18
Q

Is voltage a vector or scalar quantity?

A

Scalar

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19
Q

Is volume a vector or scalar quantity?

A

Scalar

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20
Q

What is the gradient on a distance-time graph?

A

Velocity

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21
Q

What is the gradient on a velocity-time graph?

A

Acceleration

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22
Q

What is the area under a velocity-time graph?

A

The distance

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23
Q

What is acceleration?

A

When an object speeds up or changes direction

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24
Q

What is the total area underneath a velocity-time graph?

A

The total distance travelled

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25
Q

What is the unit of force?

A

Newtons, N

26
Q

Examples of contact forces?

A
  • Friction
  • Air / Water resistance (drag)
  • Normal contact (reaction)
  • Tension
  • Upthrust
27
Q

Examples of non-contact forces?

A
  • Gravity
  • Magnetic
  • Electrostatic
28
Q

What happens when the resultant force on an object is zero?

A

The object remains stationary or continues to move at a constant speed and in the same direction.

29
Q

What is Newton’s 1st law of motion?

A

An object will remain at rest or at a constant velocity unless there is a resultant force acting on it.

30
Q

What is Newton’s 2nd law of motion?

A

The acceleration of an object is directly proportional to the resultant force and inversely proportional to the objects mass.

31
Q

What is Newton’s 3rd law of motion?

A

If object A exerts a force on object B, then object B exerts a force on object A which is equal and opposite.

32
Q

What is thinking distance proportional to?

A

Speed

33
Q

What is braking distance proportional to?

A

Speed2

34
Q

What is thinking distance?

A

The distance travelled during reaction time.

35
Q

What is braking distance?

A

The distance travelled while the brakes are applied.

36
Q

Why does thinking distance increase?

A
  • the speed increases

* the reaction time increases eg. tiredness, distraction, taken drugs / alcohol

37
Q

When does braking distance increase?

A

If the initial speed increases or if the size of deceleration is less.

38
Q

Typical speed of walking?

A

1.5 m/s

39
Q

Typical speed of running?

A

12 m/s

40
Q

Typical speed of driving?

A

20 m/s

41
Q

Typical speed of flying?

A

200 m/s

42
Q

Speed of sound in air?

A

3x10 squared

43
Q

Speed of light?

A

3x10 to the 8

44
Q

What is the weight of an object?

A

The force of gravity on it

45
Q

How to convert from Kg to N?

A

x10

46
Q

When does an object reach constant velocity?

A

When the drag force is equal and opposite to its weight

47
Q

What is terminal velocity?

A

When an object reaches a constant velocity because the drag force is equal and opposite to its weight

48
Q

What happens to the drag force when an object is released in a fluid before its terminal velocity?

A

The drag force is less than its weight before it reachers terminal velocity

49
Q

What happens to acceleration when an object is released in a fluid after its terminal velocity?

A

It is equal to zero

50
Q

What happens to the resultant force on an object released in a fluid initially?

A

The resultant force is equal to its weight, initally

51
Q

When an object is falling, what does it initially accelerate at?

A

10 m/s2

52
Q

What are plastic objects?

A

Objects that do not regain their original shape when the forces deforming it are removed

53
Q

What are elastic objects?

A

An object that regains its original shape when the forces deforming it are removed

It stores elastic potential energy when work is done on the object

54
Q

Does an elastic collision lose kinetic energy?

A

No

55
Q

What does Hooke’s law state?

A

That the extension of a spring is in direct proportion with the force applied to it

56
Q

What is the spring extension?

A

New length - original length

57
Q

What does hooke’s law only apply to?

A

Elastic materials

58
Q

What happens to a spring if the force added on the spring is larger?

A

It not longer obeys hooke’s law and does not return to its original length

59
Q

What is elastic limit?

A

The limit of proportionality (when hooke’s law no longer applies)

60
Q

What is stopping distance?

A

Thinking distance + braking distance