Topic 2 Flashcards

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1
Q

What must always be true when using the SUVAT equations of motion?

A

The acceleration must be unifrom - if the acceleration is changing, the equations are not valid.

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2
Q

What does the gradient of a distance-time graph represent?

A

Speed

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3
Q

What does the gradient of a displacement-time graph represent?

A

Velocity

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4
Q

What does the gradient of a velocity-time graph represent?

A

Acceleration

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5
Q

Describe the shape of a velocity-time graph for an object travelling with unifrom acceleration.

A

If accleration is constant, the gradient of the velocity-time graph will be constant and so it will form a straight line graph.

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6
Q

Describe the shape of a velocity-time graph for an object travelling with non-uniform acceleration

A

If acceleration is not constant, the gradient of the velocity-time graph will change and so it will form a curve

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7
Q

Compare the velocity-time graphs for a uniformly accelerating and a uniformly decelerating object.

A

For an accelerating object, the gradient will be positive

For a decelerating object, the gradient will be negative

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8
Q

What is a scalar quantity

A

A scalar quantity is one that has a magnitude but not a fixed direction

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9
Q

What is a vector quantity

A

A vector quantity is one that has a magnitude and a fixed direction

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10
Q

Give five eamples of scalar quantities

A

Distance, Speed, Mass, Energy, Temperature

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11
Q

Give five examples of vector quantities

A

Displacement, Velocity, Acceleration, Momentum, Force

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12
Q

How is a vector quantity represented on a diagram?

A

As an arrow,
The direction of the arrow represents the direction of the quantity,
The length of the arrow represents the magnitude of the quantity

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13
Q

What does resolving a vector involve?

A

Splitting the vector into two perpendicular components, vertical and horizontal.

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14
Q

Define the horizontal component of the vector in terms of V and θ

A

x = Vcos(θ)

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15
Q

Define the verticle component of the vector in terms of V and θ

A

y = Vsin(θ)

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16
Q

Describe the relationship between the perpendicular components of a vector

A

The perpendicular components are independent of each other

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17
Q

How should the components of a projectile be handled when carrying out calculations

A

The horizontal and vertical components are independent of each other and so should be treated separately
SUVAT should be used separately for each component

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18
Q

If a projectile is moving freely under gravity, what can be said about the vertical acceleration?

A

The vertical accelaration will be the acceleration due to gravity and so will have a magnitude of 9.81m/s^2

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19
Q

State Newton’s first law of motion in words

A

An object at rest will remain at rest, and an object moving with a given velocity will continue moving with that same velocity, unless acted on by an external resultant force.

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20
Q

State Newton’s second law of motion in words

A

The acceleration of an object is directly proportional to the resultant force acting on it and inversely proportional to its mass.

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21
Q

State the defining equation of Newton’s second law of motion.

A

F=ma

Force (N) = Mass (kg) x Acceleration (m/s^2)

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22
Q

Can an object travelling with constant speed change direction, without an external force acting?

A

For an object to change direction, its velocity must change. This means there must be an acceleration. An acceleration cannot occur without an external resultant force acting.

23
Q

Describe the forces acting on an object travelling at terminal velocity

A

The forces are balanced in both the vertical and horizontal components of its motion
There is no resultant force, and therefore no acceleration

24
Q

What is meant by terminal velocity?

A

For a given set of conditions, the terminal velocity is the maximum speed of the object. An object has zero acceleration at terminal velocity

25
Q

State the equation used to calculate the weight of an object

A

W=mg

Weight = Mass x Gravitational Field Strength

26
Q

What is the unit of weight?

A

Newtons, N

27
Q

State Newton’s third law of motion in words.

A

Every action has an equal and opposite reaction. This means that there is always a pair of forces acting on interacting objects, equal in magnitude, but in opposite directions

28
Q

State the equation for momentum

A

p=mv

Momentum = Mass x Velocity

29
Q

What is the unit of momentum?

A

kgm/s

30
Q

What is the consequence of the linear conservation of momentum

A

The total momentum of a system before an event is always equal to the total momentum of the system after the event.

31
Q

What is a moment?

A

A moment is the turning effect of a force

32
Q

State the equation used to calculate the moment of a force.

A

Moment of a force = Force x Distance

33
Q

What distance must be used when calculating a moment?

A

The perpendicular distance between the line of action of the force and the axis of rotation

34
Q

What is the unit of a moment?

A

Nm

35
Q

What is the principle of moments?

A

For an object to be in equilibrium, the sum of the clockwise moments about a point must be equal to the sum of the anticlockwise moments

36
Q

What is an object’s centre of gravity

A

The single point through which the object’s entire weight can be said to act

37
Q

What will occur if the line of action, an object’s centre of gravity, lies outside its base?

A

The object’s weight will produce a resultant moment and so if unsupported, the object may topple.

38
Q

State the equation used to calculate the work done by a force

A

W=FΔs

Work Done = Force x Change in Distance

39
Q

What force is used when calculating the work done by a force over a distance?

A

The component of the force that is in the direction of the object’s motion

40
Q

What is the unit of work?

A

Joules, J

41
Q

What is the work done by the force, F when it moves the object a distance of x? (Triangle with angle θ, hypotinuse of F, horizontal x)

A

Work Done = Fcos(θ) x

42
Q

What form of energy do all moving objects have?

A

All moving objects have kinetic energy

43
Q

State the equation used to calculate the kinetic energy of an object

A

Ek = 1/2 mv^2

Kinetic energy = 1/2 x Mass x Velocity^2

44
Q

What form of energy does a raised object have?

A

Gravitational Potential energy

45
Q

State the Equation used to calculate gravitational potential energy

A
GPE = Mass x Gravitational Field Strength x Height
GPE = mgh
46
Q

What is the conservation of energy?

A

The law of conservation of energy states that energy cannot be created or destroyed - it can only be transferred between different forms

47
Q

What is power

A

The rate at which energy or work is done

48
Q

State two equations used to calculate power

A

P=E/t

P=W/t

49
Q

What is the unit of power?

A

Watt, W

50
Q

What is the waste energy of an electrical appliance?

A

The waste energy is the energy that is not used for the appliance’s intended purpose.

51
Q

State the equation relating energy and efficiency

A

Efficiency = Useful energy output / Total energy input

52
Q

State the equation relating power and efficiency

A

Efficiency = Useful power output / Total power input

53
Q

What is the unit of efficiency?

A

Efficiency is a ratio and so doesn’t have an associated unit