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P2 1 Motion.
Speed (m/s)= Distance (m) ÷ Time (s)
The slope on a distance-time graph represents speed.
The steeper the slope, the greater the speed.
Velocity is speed in a given direction.
The acceleration of any object is the rate at which its velocity changes. It's a measure
of how quickly an object speeds up or slows down.
Acceleration (m/s²) = Change on velocity (m/s) ÷ Time taken for change (s)
Deceleration is a negative acceleration. It describes an object that is slowing down.
The slope of a velocity-time graph represents the acceleration of the object. The
steeper the slope, the greater the acceleration.
The area underneath the line on a velocity-time graph represents the total distance
P2 2 Speeding Up and Slowing Down.
Force is measured in Newton's (N).
When a stationary object rests on a surface it exerts a downward force. The surface
it rests on exerts an upward force. These 2 forces are equal and opposite, so the
object remains stationary.
A number of forces acting on an object can be replaced by a single force. This force
has the same effect on the object as the original forces all acting together. This is
called the resultant force.
If the resultant force is not zero, then the object remains stationary if it was at rest
OR it continues to move at the same speed and in the same direction if it was
If the resultant force is not zero then the movement of the object depends on the
size and direction of the resultant force.
Friction is a force that occurs when:-
o An object moves through a medium e.g. air or water.
o Surfaces slide past each other.
Friction works against the object, in the opposite direction to which it is moving.
Thinking distance + Braking distance = Stopping distance
Thinking distance The distance travelled by the vehicle during the driver's reaction
Braking distance The distance travelled by the vehicle under the braking force.
The overall stopping distance is increased:-
o When the vehicle is travelling at greater speeds.
o When there are adverse weather conditions e.g. wet or icy roads, poor
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When the driver is tired, or under the influence of drugs or alcohol and can't
react as quickly as normal.
o The vehicle is in a poor condition e.g. it has under-inflated tyres.
If an unbalanced force acts on an object:-
o The bigger the force the greater the acceleration.
o The bigger the mass, the smaller the acceleration.…read more
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Metals conduct electricity because they contain delocalised electrons in there
A charged conductor can be discharged. This is done by connecting the conductor to
the Earth, to lose the charge.
o If a conductor touches a negatively charged dome, electrons flow from the
dome to earth, via the conductor, until the dome is completely discharged.…read more
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P2 6 Mains Electricity
An alternating current changes the direction of flow black and forth continuously.
Frequency The number of cycles passing through each second.
Live Wire It alternates between a positive and negative voltage.
Neutral Wire It stays at a voltage close to zero.
Circuit Breaker It automatically breaks an electric circuit if it becomes overloaded.
Power (W) = Energy Transformed (J) ÷ Time (s).
Power (W) = Potential difference (V) × Current (A).…read more