Mechanics 2 - Linear and Projectile Motion Flashcards

1
Q

What is displacement and how is it different to distance?

A

Displacement is a measure of the line connecting the starting point to the finishing point.

Distance is a measure of the total length of the path travelled.

Also distance is a scalar and displacement is a vector.

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2
Q

What does a straight line on a distance-time graph represent?

A

A constant speed.

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3
Q

How is acceleration defined?

A

Acceleration is the rate of change of velocity.

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4
Q

How is speed different to velocity?

A

Speed is the rate of change of distance.

Velocity is the rate of change of displacement.

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5
Q

Describe the motion of this ball

A

Ball is moving to the right and speeding up.

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6
Q

Decribe the motion of this ball.

A

Ball is moving to the left and speeding up.

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7
Q

Describe the motion of this ball.

A

Ball is moving to the right and slowing down.

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8
Q

Describe the motion of this ball.

A

Ball is moving to the left but slowing down.

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9
Q

Is the ball moving to the right?

A

Only if the velocity vector is also acting to the right.

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10
Q

What does a straight line on a displacement-time graph represent?

A

A constant velocity.

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11
Q

What does a curve with an increasing gradient represent on a displacement-time graph?

A

An increasing velocity (acceleration)

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12
Q

What does a curve with a decreasing gradient represent on a displacement-time graph?

A

A decreasing velocity (decceleration)

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13
Q

What does a negative gradient on a displacement-time graph represent?

A

A negative velocity (travelling back to where it started)

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14
Q

What does a straight line on a velocity-time graph represent?

A

A constant acceleration.

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15
Q

What does a curve with an increasing gradient represent on a velocity-time graph?

A

An increasing acceleration.

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16
Q

What does a curve with a decreasing gradient represent on a velocity-time graph?

A

A decreasing acceleration.

17
Q

What does a negative gradient on a velocity-time graph represent?

A

A negative acceleration.

18
Q

What does this graph show?

A

A ball bouncing off a surface

(Dotted lines represent the bounce)

(Red lines represent the ball accelerating towards the ground)

19
Q

What does the acceleration time graph of a ball in freefall look like?

A

Constant acceleration of 9.81ms-2

20
Q

What does the area of a speed-time graph represent?

How about a velocity-time graph?

A
21
Q

What’s wrong with this?

A

Displacement takes direction into account.

It should be…

22
Q

When can you use this equation?

A

When the acceleration = 0 (constant velocity)

Or to work out an average speed

23
Q

When can you use SUVATs?

A

When acceleration is constant

Or if object has stages of constant acceleration

24
Q

Why can’t you use SUVAT’s when working with this graph?

A

Because the acceleration (gradient) is changing

25
Q

What does it mean if an object is in freefall?

A

Only weight is acting on the object

It has a constant acceleration of 9.81ms-2 acting downawards (on Earth)

26
Q

If one ball is dropped as another is projected horizontally which hits the ground first?

A

They both hit the ground at the same time…

Both in freefall so accelerate at 9.81ms-2

Vertical motion independent of horizontal motion

27
Q

What’s wrong with this labelling?

A

Initial velocity and final velocity are not 0

28
Q

In projectile motion when is the vertical component of the velocity 0?

A

At the peak of a parabola

Not at the start or end

29
Q

How do you start a question involving angled projectile motion?

A

Resolve the velocity into vertical and horizontal components and fill out the corresponding SUVATs

30
Q

What is wrong here?

A

The acceleration is only 9.81ms-2 if the object is in freefall