# Work, Energy And Momentum

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• Created by: Josh
• Created on: 04-01-11 16:40

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P2: Work, Energy And Momentum
As physics is a hard topic, the specification of the exams has
been used to make notes on only the area we NEED to know. The
notes have been written in small sentence format for easier
learning.
Speed
The speed is how fast an object is moving
Measured in m/s
To calculate speed you use this formula:
Speed (m/s) = distance travelled (m) / time taken (s)
Distance Time Graphs
The slope of a distance time graph represents speed
Velocity
Velocity is speed in a given direction
Acceleration
The acceleration of an object is the rate at which its velocity
changes
Calculated using this formula:
Acceleration (m/s²) =change in velocity(m/s) / timetaken for
change
Velocity time Graph

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The slope of a velocity time graph represents acceleration
The area under a velocity time graph represents the distance
travelled
Equal and Opposite Forces
Whenever two objects push or pull on each other, they exert an
equal but opposite force on each other.
The unit of force is the newton (N)
Example:
A boxer who punches an opponent with a force of 100N
experiences a reverse force of 100NJ form his opponent.…read more

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When a vehicle travels at a steady speed the frictional forces
balance the driving force
Stopping Distance
The greater the speed of the vehicle the greater the braking force
needed to stop it in a certain distance
The stopping distance of the vehicle depends on the distance the
vehicle travels during the driver's reaction time and the distance it
travels under the braking force
The reaction time can be affected by:
Tiredness
Drugs
Alcohol
A vehicles braking distance can be affected by:

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When a force causes a body to move through a distance, energy
is transferred and work is done
Work done = energy transferred
Work done (J) =force applied(N) X distance moved (m)
Work done against frictional forces is mainly transformed into heat
For an object that is able to recover its original shape, elastic
potential is the energy stored in the object when work is done on
the object to change its shape
Kinetic Energy
The kinetic energy of a body depends in its mass…read more

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Speed = the rate at which an object moves
Velocity = the speed at which an object moves in a particular
direction
Velocitytime graph = represents acceleration (velocity against
time taken)
Energy = the capacity of a physical system to do work measured
in Joules (J)
Force = a push or pull acting on an object
Friction = The resistive force between two surfaces as they move
over eachother
Joule = a measure of energy and work done
Momentum = a measure of the state…read more