# Topic 1- Motion and Forces

What is a scalar quantity?
A physical quantity which has only magnitude and no direction. Examples: speed, distance, mass, energy, temperature, time, etc
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What is a vector quantity?
A physical quantity which has both magnitude and direction. Examples: force, velocity, displacement, weight, acceleration, momentum, etc
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What is velocity?
Velocity is a vector. It is speed in a stated direction.
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What is the equation for speed?
speed (m/s) = distance (m) ÷ time (s)
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Distance/Time Graphs
SLOPE- is the gradient and can give you the speed. FLAT- this shows where the vehicle has topped moving. STEEPER SLOPES- this shows that the faster the object moves the stepper the line is. CURVES- shows acceleration.
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What is the equation for acceleration?
acceleration (m/s2) = change in velocity (m/s) ÷ time (s)
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Velocity/Time Graphs
GRADIENT- shows acceleration FLAT SECTIONS- represents a steady speed UPHILL- shows acceleration DOWNHILL- deceleration CURVE-shows a changing acceleration
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What is Newton's First Law?
Newton's law states an object at rest will stay at rest and an object in motion will stay in motion with the same speed and direction unless acted upon by unbalanced force.
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Newton's Second Law...(equation for force)
force (N) = mass (kg) x acceleration (m/s2) F=mxa
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What is the equation for weight?
weight (N) = mass (kg) x gravitational field strength (N/kg) W=mxg
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What is a centripetal force?
It is when if an object is travelling in a circle at at constant speed, it is constantly changing direction, so it is constantly changing velocity. This means it's accelerating. This means there must be a resultant force. This force acts towards...
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What is a centripetal force? (continued)
... This force acts towards the centre of the circle. This force that keeps something moving in a circle is called a centripetal force.
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What is inertial mass?
The tendency to keep moving with the same velocity is called inertia. An object's inertial mass measures how difficult it is to change the velocity of an object. Also it can be worked out by rearranging the formula F= m x a
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What is Newton's Third Law?
Newton's Third Law says: Whne two objects interact, the forces they exert on each other are equal and opposite.
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What is the equation for momentum
momentum (kg m/s) = mass (kg) x velocity (m/s) p = m x v
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Changes In Momentum
When a resultant force acts on a object for a certain amount of time, it causes a change in momentum. The bigger the force, the faster the momentum changes.
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What is the equation for change in momentum?
force (N) = change in momentum (kg m/s) ÷ time (s)
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How do you work out the stopping time?
Stopping Distance = Thinking Distance + Braking Distance
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How can you measure the human reaction time?
1) Have your hands resting on the edge of a table and get someone to hold a ruler between your thumb and forefinger. 2) Without a warning, get the other person to drop the ruler and see how long it takes to catch it...
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What are factors which may affect thinking and stopping distance?
*greater speed *tiredness *alcohol *drugs *distraction *greater speed *poor road distractions *car conditions *how many people are in the vehicle.
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How can you measure the human reaction time? (continued)
3)The measurement on the ruler is how far it took for a reaction to happen. 4) To see how long the ruler was for falling for we use the equations-> a=v-u ÷t and v2-u2=2 x a x X 4) To get accurate results repeat 3 times
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## Other cards in this set

### Card 2

#### Front

What is a vector quantity?

#### Back

A physical quantity which has both magnitude and direction. Examples: force, velocity, displacement, weight, acceleration, momentum, etc

### Card 3

#### Front

What is velocity?

### Card 4

#### Front

What is the equation for speed?

### Card 5

#### Front

Distance/Time Graphs