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Definition
How far you travel in a certain period of time.
In Physics we usually measure the distance travelled in metres per second.
Speed = distance / time |
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| Velocity is a speed and direction. |
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| Acceleration describes how the speed of an object changes in fixed amount of time. In Physics we measure the change in speed in metre per second per second or m/s2. |
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Definition
The steepness of a slope of a line graph.
On a distance-time graph the gradient is equal to the speed of the object.
On a speed-time grpah the gradient is equal to the acceleration of the object. |
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Definition
| The forces on an object cancel each other out so the resultant force is zero. The forces are usually the same size but in opposite directions. |
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Definition
If the forces on an object are unbalanced then the resultant force is not zero.
The forces acting on an object are not the same size and/or not in opposite directions. |
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Definition
Forces in the same direction add together.
Forces in the opposite direction take away.
The net single force is called the resultant force. |
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The stoppng distance is the distance a vehicle travels from when the driver sees the incident until the car comes to a stop.
The stopping distance can be divided into two parts, the thinking distance and the breaking distance. |
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Definition
The distance a vehicle travels before the driver reacts to the incident.
This depends on the drivers reaction time (affected by tiredness, talking on mobile phones, drinking alcohol for example) and the speed of the vehicle. |
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Definition
The distance the vehicle travels once the brakes are applied until it comes to a stop.
This is affected by friction (tyres, ground or brakes), speed of the vehicle and the mass of the vehicle. |
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Term
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Definition
Kinetic energy describes the energy of a moving object.
Kinetic energy is proprtional to mass (whatever happens to one will happen to the other. If you double one then you double the other)
However kinetic energy is proportional to the speed of the object squared. (if you double the speed the kinetic energy would quadruple!) |
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Definition
Energy cannot be made or destroyed it can only be converted.
When energy is converted from one type to another, scientists say that work has been done.
Work = Amount of energy converted. |
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Definition
Momentum is another way to describe the motion of an object which is particularly useful for understanding the effects of collisions.
Momentum is measured in kgm/s. |
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Term
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Definition
The rate at which momentum changes describes the force needed to cause it.
If the change in momentum of an object happens quickly (small amount of time) then the force to cause the change in momentum is very big.
If the change in momentum of an object happens slowly (large amount of time) then the force to cause the change in momentum is very small. |
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Term
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Definition
Momentum is not lost or made unless a force acts on the object.
Total momentum before = Total momentum after |
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