Physics- P4 Revision



  • Acceleration= Change in Velocty/Time,
  • Speed= Distance/Time,
  • Velocity= Displacment/Time,
  • Wight= Mass*Gravitaion Field Strenght,
  • Force= Mass*Acceleration,
  • Momentum= Mass*Velocity,
  • Gravitatinol Potential Energy(GPE)= Maa*Gravitatnol Field Strenght*Height,
  • Kinetic Energy= 0.5*Mass*Velocity2,
  • Power= Work Done/Power,
  • Final Velocity2= (Inital Velocty)2+(2*Acceleration*Distance),
  • Moment= Force*Distance from piviot,
  • Total Stopping Time= Thinking Distance+Braking Distance,
  • Reaction Time= 2*Reaction Distance/10,   (Square root the answer),
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Types Of Energy




Can be stored

Can't be stored

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The Principle of......

The Principle of Conservation Energy

  • Energy cannot be created or destroyed but can be transferred from 1 type to another,
  • Another name for energy transferred is work done,

The Principle of Moments

  • If the anti-clockwise moment & clock-wise moment are equal, then the trebuchet is balanced,
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Collision Time

The greater the time to stop the smaller the force felt, this time is often called the collision time.

Examples where increased collision time reduces forces:

  • Bending elbows to catch a ball,
  • Airbags,
  • Vertical Seat Belts,
  • Crumple Zones,
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Gravity & GPE

Gravity acts toward the center of the earth.

The GPE on the earth is 10N/kg,

The GPE on the moon is 1.6N/kg,

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Typical Speeds

  • Speed of Light= 300,000,000m/s,
  • Speed of Sound= 330m/s,
  • Wind- Gental Breeze- 5m/s,
               Strong Breeze- 12m/s,
  • Walking- 4km/h --  1m/s,
  • Cycling- 24km/h -- 6m/s,
  • Running- 16kh/h -- 4m/s,
  • Car in Town- 48km/h -- 12m/s
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Newtons Laws

Newtons 1st Law

A stationary object, with no resultant force, will keep still,
A moving object, with no resultant force, will keep moving at a constant speed,

Newtond 2nd Law

A stationary object, with a resultant force, will start moving,
A moving object, with a resultant force, will speed up/ slow down or change direction,

Newtons 3rd Law

If object A exerts a force on object B, then object B exerts an equal but opposite force on object A,

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  • Acceleration can mean: Speeding up, Slowing Down or Changing Direction,
  • Displacement: Shortest distance between 2 points,
  • Mass is the amount there is of something,
  • Weight is the amount of force on something,
  • Momentum is a vector quantity, meaning it has a direction and a speed,
  • Power is the rate at which work is done,
  • The turning effect of a force is called a moment,
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Circular Motion

  • Any object needs a force to travel in a circle,
  • The eath goes at a constant speed, not a constant velocity,
  • The speed may be constant but the velocity changes because it is going in a different direction,
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Inertial Motion

The reluctance of a body to start moving, a force is needed to start something moving.

Mass= Force/ Acceleration.


A lorry of mass 20,000kg traveling at 108km/h braked and stops in 102m.
Calculate: a- Deceleration= -3.75m/s,
                 b- Braking Force= -75,000N,

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