Topic 2 - Mechanics (P1) Flashcards by Jack Sinclair

What is the definition of speed?

Speed is the rate of change of distance.

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What is the definition of velocity?

Velocity is the rate of change of displacement.

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How is velocity measured?

Velocity is measured in ms⁻¹.

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What is the difference between a vector quantity and a scalar quantity?

Vector quantities have both magnitude and direction; scalar quantities have only magnitude.

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Give three examples of vector quantities.

Displacement
Velocity
Acceleration

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Give three examples of scalar quantities.

Distance
Speed
Mass

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Calculate the distance travelled by a man who runs around a 400m athletics track in 50 seconds.

Distance travelled = 400 m.

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What is the displacement of a man who runs around a 400m athletics track?

Displacement = 0 m.

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What is the average speed of a man who runs around a 400m track in 50 seconds?

Average speed = 8 m/s.

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What is the average velocity of a man who runs around a 400m track?

Average velocity = 0 m/s.

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Calculate the speed of a car that travels 200 km in 4 hours.

Speed = 50 km/h.

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Calculate the velocity of a car that travels 200 km in a north-easterly direction in 4 hours.

Velocity = 50 km/h north-east.

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What is the average speed for a 135 km journey that takes 2 hours?

Average speed = 67.5 km/h.

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What is the average speed for a 135 km journey that takes 2 hours in m/s?

Average speed = 18.75 m/s.

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Does a satellite in a circular orbit around the Earth have constant speed, constant velocity, both, or neither?

Constant speed but not constant velocity.

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A car travels at a steady speed of 30 m/s, how far ahead of a coach traveling at 25 m/s will the car be after 1 minute?

Car will be 300 m ahead.

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How far ahead of the coach will the car be after 30 minutes?

Car will be 9000 m ahead.

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What does acceleration tell us?

Acceleration tells us how much an object speeds up by every second.

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How is acceleration measured?

Acceleration is measured in ms⁻² (m/s/s).

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If a car accelerates at 6 m/s², what does this mean?

The car’s speed increases by 6 m/s every second.

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What is acceleration defined as?

Acceleration is defined as the rate of change of velocity.

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Calculate the car’s velocity after 2 seconds if it accelerates uniformly at 12 m/s² from rest.

Velocity after 2 seconds = 24 m/s.

Calculate the car’s velocity after 15 seconds if it accelerates uniformly at 12 m/s² from rest.

Velocity after 15 seconds = 180 m/s.

Calculate the car’s velocity after 30 seconds if it accelerates uniformly at 12 m/s² from rest.

Velocity after 30 seconds = 360 m/s.

Calculate Jasper's acceleration if he accelerates from rest to 20 m/s in 5 seconds.

Jasper's acceleration = 4 m/s².

Calculate the carrot's acceleration if it accelerates from rest to 200 m/s in 0.5 seconds.

Carrot's acceleration = 400 m/s².

Calculate the acceleration of a man who increases his speed from 2 m/s to 8 m/s in 5 seconds.

Acceleration = 1.2 m/s².

Calculate the deceleration of a car that slows down from 50 m/s to 20 m/s in 5 seconds.

Deceleration = 6 m/s².

If a cyclist accelerates at 2.5 m/s² from an initial speed of 20 m/s, how long until it reaches 60 m/s?

Time = 16 seconds.

If a car decelerates at -12 m/s² from 60 m/s, how long will it take to stop?

Time to stop = 5 seconds.

What are the four equations of motion?

1. v = u + at 2. s = ut + 1/2 at² 3. v² = u² + 2as 4. s = ½(u + v)t

What does 'u' represent in the equations of motion?

Initial velocity

What does 'v' represent in the equations of motion?

Final velocity

What does 's' represent in the equations of motion?

Distance travelled

What does 't' represent in the equations of motion?

Time taken

What does 'a' represent in the equations of motion?

Constant acceleration

Fill in the blank: Use the equations of motion only if the acceleration is _______.

constant

Calculate the acceleration if a goat accelerates from rest to a final velocity of 200 ms-1 in 5 seconds.

40 ms-2

If a car travels 80m in 3 seconds and slows down to a stop, what was the initial velocity?

26.67 ms-1

Derek is running at 3 ms-1 and accelerates at 0.5 ms-2 over a distance of 40 m. What is his final velocity?

10 ms-1

Calculate the time it takes for George the lemming to fall from a height of 260 m assuming gravity is 10 ms-2.

7.2 seconds

A car travels 100m in 4 seconds from rest. What is the car’s acceleration?

12.5 ms-2

A pigeon decelerates at -2 ms-2 from a speed of 10 ms-1. How long does it take to stop?

5 seconds

If a child is thrown vertically upward at 30 ms-1, what is the maximum height they reach?

45 m

A car has an initial velocity of 20 m/s and travels 200 m in 5 seconds. What is the car’s acceleration?

0 ms-2

A rabbit starts at 2 m/s and accelerates at 3 m/s² over a distance of 10 m. Calculate the rabbit’s final speed.

8 m/s

Calculate the time it takes for the rabbit to cover 10 m if it starts at 2 m/s and accelerates at 3 m/s².

2 seconds

Sid the lemming falls off a cliff and takes 10 seconds to hit the ground. What is the height of the cliff?

500 m

What is Sid the lemming's velocity just before he hits the ground?

100 ms-1

A car skids to a halt from 50 ms-1 in 2.5 seconds. What is the distance it stops over?

125 m

A car accelerates at 3.6 ms-2 from rest for 3 seconds. What distance does it travel?

16.2 m

If a teddy bear is dropped and its speed just before it hits the ground is 30 m/s, how tall is the building?

45 m

A boat traveling at 30 m/s decelerates to 10 m/s at a rate of 2.3 m/s². How long does it take to do this?

8.7 seconds

A ball is thrown upwards and reaches a height of 400 m. What was the initial velocity of the ball?

28.0 m/s