Chapter 8: Motion_checked Flashcards

1
Q

What is the difference between a scalar and a vector?

A

A scalar has no direction - it’s just an amount of something
A vector has a magnitude and a direction

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2
Q

How do you find the resultant vector?

A

Adding two or more vectors together

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3
Q

Define speed

A

How fast something is moving, regardless of direction

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4
Q

Define displacement

A

How far an object’s travelled from its starting point in a given direction

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5
Q

Define velocity

A

The rate of change of an object’s displacement (its speed in a given direction)

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6
Q

What is instantaneous speed?

A

The speed of an object at any given moment in time

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7
Q

What is the average speed?

A

Total distance covered, over the total time elapsed

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8
Q

What is another way of saying uniform acceleration?

A

Constant

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9
Q

Define free fall

A

The motion of an object undergoing an acceleration due to gravity, ‘g’.

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10
Q

What is/are the force(s) acting on an object in free fall?

A

Weight

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11
Q

Describe the rate of free fall for different objects

A

All objects free fall at the same rate

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12
Q

What is the main uncertainty in the experiments (light gates and trapdoor) to find the value g?

A

The height h

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13
Q

What is parallax, in the context of uncertainties?

A

Systematic error due to looking at the ruler at an angle

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14
Q

In a graph of displacement against time, how can you tell that something is accelerating?

A

Graph is curved

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15
Q

What does the graph (displacement against time), look like if the object is accelerating at a uniform rate?

A

Rate of change of the gradient will be constant

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16
Q

In a displacement time graph:
If there are two objects, both accelerating, how can you tell which is accelerating more?

A

Steeper curve

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17
Q

In a displacement time graph:
If there are two objects, both accelerating, how can you tell which is accelerating less?

A

Shallower curve

18
Q

In a displacement time graph:
How can you tell if object is decelerating?

A

The line has a deceasing gradient

19
Q

What does the gradient of a displacement time graph tell you?

A

The velocity

20
Q

How do you find the instantaneous velocity of an object, using the displacement time graph?

A

Draw a tangent and calculate the gradient

21
Q

Uniform acceleration is always a [], on a velocity time graph

A

Straight line

22
Q

The steeper the gradient, the [] the acceleration

(Velocity time graph)

A

greater

23
Q

What is the area under a velocity time graph?

A

Displacement

24
Q

What shows that the acceleration is increasing on a velocity time graph?

A

Increasing gradient

25
Q

What shows that the acceleration is decreasing on a velocity time graph?

A

Decreasing gradient

26
Q

What do free-body force diagrams show?

A

Show a single body on it own

27
Q

Which forces are shown on a free body diagram?

A

Forces that act on the body, but not the forces it exerts on the rest of the world

28
Q

If a body is in equilibrium, the forces acting on it will be []

A

Balanced

29
Q

How do you find the resultant force on a body?

A

Add the vectors (of the forces) together

30
Q

Describe the accuracy of data loggers

A

They do not have human error and can calculate the velocity and display it in real time – saving time and allowing comparisons between experiments to be easily made

31
Q

Briefly describe how iterative methods can be used for modelling displacement/velocity

A

Velocity and displacement are calculated over lots of small tiny increments/intervals of time to model their motion over a period of time

32
Q

Give an example of a problem with iterative models

A
  • Graphs don’t look realistic
  • They assume no change occurs within the sampled
    time intervals (eg. if the calculation is applied at 5 second intervals, it is assumed that the
    motion is constant between 5 and 10 seconds).
33
Q

How can iterative models be improved?

A

The accuracy of iterative models can
always be improved by decreasing the time interval.

34
Q

What are vectors?

A

Quantities with both magnitude and direction

35
Q

Which suvat equation is not given in booklet
s
u
v
t

A
  • s = (u+v / 2) * t
    s - displacement / m
    u - initial velocity / ms-1
    v - final velocity / ms-1
    t - time / s
36
Q

What is an advantage of iterative models

A

Iterative models can be used for difficult calculus problems

37
Q

How do you calculate a new value of v

A

a = Δv / Δt

=> Δv = aΔt

38
Q

How do you calculate a new value of s

A

v = Δs / Δt

=> Δs = vΔt

39
Q

*How do you calculate a value of acceleration for iteration

A

This is an example that has been given on past exam papers

a = 9.8 - kv<sup>2</sup> 
k = constant
40
Q

What does the gradient of a velocity time graph show you?

A

Acceleration