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42 Cards in this Set
- Front
- Back
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What is the difference between a vector and a scalar? |
A vector has magnitude (size) and direction whereas a scalar has size only. |
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What is the difference between speed and velocity? |
Speed is a scalar and velocity is a vector - speed in a particular direction |
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What words should we use when describing motion? |
Speed, direction, constant (no acceleration or changing speed and/or direction - acceleration, |
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What can help us to describe the movement of a body? |
Graphs: these may be distance-time graphs or velocity-time graphs. |
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What does the slope (gradient) of a distance-time graph represent? |
Speed |
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What is the velocity of a body? |
It is its speed in a given direction. |
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What is the acceleration of a body? |
It is the rate of change of velocity (change in velocity divided by time). |
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What is the unit of velocity? |
Metres per second (m/s) |
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What is the S.I. unit of acceleration? |
Metres per second squared |
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What is the S.I. unit of distance? |
metres (m) |
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What is the S.I. unit of time? |
second (s) |
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How can you find acceleration from a velocity/time graph? |
The slope (gradient) of a velocity-time graph represents acceleration. |
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How can you find distance travelled from a velocity/time graph? |
The area under a velocity-time graph represents distance travelled. |
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How can you change the speed of a body |
Make a force act on it. |
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What is acceleration evidence of? |
A 'net force' or 'unbalanced forces' acting on a body. |
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What happens whenever two bodies interact? |
The forces they exert on each other are equal and |
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What is a resultant force? |
A number of forces acting on a body may be replaced by a single force which has the same effect on the body as the original forces all acting together. |
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If the resultant force acting on a stationary body is zero, what will the body do? |
The body will remain stationary. |
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If the resultant force acting on a stationary body is not zero, what will the body do? |
The body will accelerate in the direction of the resultant force. |
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If the resultant force acting on a moving body is zero the body, what will the body do? |
It will continue to move at the same speed and in the same direction. |
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If the resultant force acting on a moving body is not zero, what will the body do? |
The body will accelerate in the direction of the resultant force. |
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What does it mean when a vehicle travels at a steady speed? |
It means that the frictional forces balance the driving force. |
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How is braking force related to stopping distance? |
The greater the speed of a vehicle the greater the braking force needed to stop it in a certain distance. |
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What two parts make up the stopping distance of a vehicle? |
The stopping distance of a vehicle depends on the distance the vehicle travels during the driver’s reaction time and the distance it travels under the braking force. |
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What can affect a driver’s reaction time? |
Tiredness, drugs and alcohol. |
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What can affect vehicle’s braking distance? |
Adverse road and weather conditions and poor condition of the vehicle. |
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How does speed through a fluid affect friction? |
The faster a body moves through a fluid the greater the frictional force which acts on it. |
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What is terminal velocity? |
The speed reached when a body falls through a fluid and weight equals drag. |
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How is kinetic energy related to speed? |
The faster the speed the higher the kinetic energy. |
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What happens when a force causes a body to move through a distance? |
Energy is transferred and work is done. |
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What is 'work'? |
Work is done whenever energy is transferred - it is the result of energy transfer. |
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What energy transfer occurs when work done against frictional forces? |
Kinetic energy is transformed into heat. |
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When work is done on the object to change its shape how can that energy be stored? |
As elastic potential energy. |
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What does kinetic energy of a body depend on? |
The kinetic energy of a body depends on its mass and its speed. |
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What two things increase with speed? |
The faster a body is moving the more kinetic energy and momentum is has. |
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When working out what happens to bodies as a result of explosions or collisions; which is the most useful to think about, momentum or energy change? |
Momentum. |
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What is the law of conservation of momentum? |
The sum of the momentum of bodies before an event is equal to the sum of the momentum after the event as long as no external forces act. |
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Is momentum a scalar or a vector? |
A vector - momentum has both magnitude and direction. |
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What causes a change in momentum? |
When a force acts on a body that is moving, or able to move, a change in momentum occurs. |
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What happens when a change in momentum of a body occurs? |
Acceleration |
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What is the impulse of a force? |
The force multiplied by the time it acts. |
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What is impulse equal to? |
The change in momentum it produces. |
