Flashcards in Motion, Force And Energy Deck (40):

1

## vector

### Vector quantities have a magnitude and a direction

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## Scalar

### Have quantities and no direction

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## Speed and velocity

###
Both measure how fast your going

Speed is scalar

Velocity is a vector

Means velocity can change if speed is staying the same

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## D = s x t

### Distance = speed x time

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## Scalar quantaties

###
-Speed

-Distance

-Mass

-energy

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## Vector quantatities

###
-Force

-Velocity

-Displacement

-Weight

-Acceleration

-Momentum

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## Distance time graph

### -The gradient represents the speed; the steeper the line the faster the speed

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## Velocity time graph

###
-Horizontal line= constant velocity

-Upwards sloping line = acceleration

-Downwards sloping line = deceleration

-Total distance travelled is shown by the area under the graph

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## a = v-u/t

###
acceleration (metre per second squared, m/s2) = change in

velocity (metre per second, m/s) ÷ time taken (second, s)

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## constant acceleration

### uniform acceleration

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## v − u = 2× a× x

###
(final velocity)2 ((metre/second)2, (m/s)2) – (initial velocity)2

((metre/second)2, (m/s)2) = 2 × acceleration (metre per

second squared, m/s2) × distance (metre, m)

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## Typical speeds

###
-walking = 1.4m/s

-running = 3m/s

-Cycling = 5.5m/s

-cars in built up area = 13m/s

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## Equipment for measuring speed

### light gates

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## Newton's first law of motion

### An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force

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## If a stationary object experiences a resultant force of not zero

### It will accelerate in the direction of the resultant force

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## If a moving object experiences a resultant force of not zero

### It will accelerate in the direction of the resultant force

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##
F = m× a

###
force (newton, N) = mass (kilogram, kg) × acceleration

(metre per second squared, m/s2)

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## W = m× g

###
weight (newton, N) = mass (kilogram, kg) × gravitational field

strength (newton per kilogram, N/kg)

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## Circular motion

### Objects travelling in a circular motion are prevented from moving off in a straight line by centripetal force. This resultant force pulls objects toward the centre of the circle, continually changing the direction that an object is travelling in to keep it in circular motion.

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## Inertia

### Inertia is the tendency for motion to remain unchanged.

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## Inertial mass

###
An object's inertia mass measures how difficult it is to change the velocity of an object

m = f/a

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## Newton's third law is:

### For every action, there is an equal and opposite reaction.

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## What is the momentum of a stationary object?

### zero

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## p = m × v

###
p is the momentum in kilograms metres per second, kg m/s

m is the mass in kilograms, kg

v is the velocity in m/s

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## Conservation of momentum

### The total momentum of an object before an event is equal to the total momentum after the event

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## When does momentum change?

###
The momentum of an object can change if:

The object speeds up or slows down

The object changes direction

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## F = mv - mu / t

###
Force (newton, N) = change in momentum (kilogram

metre per second, kg m/s) ÷ time (second, s)

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## Factors affecting the thinking distance

###
-Reaction time: increased by tiredness, drugs, alcohol and distractions

-Speed: the faster you're going the further your travel during reaction time

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## Factors affecting the stopping distance

###
-Speed: faster you're going longer it take to stop

-Mass of car: heavy wont stop as fast as empty car

-Wet or icy conditions

-Worn brakes/ Worn tyres

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## Large decelerations

### Large decelerations can cause serious injury as it requires a larger force

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## Braking

### To stop a car from moving we need to apply a force to transfer its kinetic energy into other forms - such as heat. This is what brakes do - they apply a force in the opposite direction to the motion of the car. This causes deceleration and eventually the car stops.

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##
what is weight

### the force of gravity acting on an object

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##
what is mass

### the measure of how many atoms in an object

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## formula for calculating weight

### weight = mass x gravity

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##
gravitational field strength of Earth

### 10N/kg

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## what is weight measured in

### Newtons (it's a force)

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##
what is the difference between mass and weight

### weight can change depending on the gravitational field strength whereas mass has the same value anywhere

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## formula for calculating mass

### mass = weight / gravitational field strength

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## how can the momentum of an object be increased

###
- by increasing the mass of the object

- or by increasing its velocity

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