Physics

• average speed = total distance/total time
• average speed = initial speed + final speed/2
• Average velocity = total displacement/total time
• Acceleration = initial speed - final speed/time taken
• Rate of change of speed = final speed - initial speed/time
• Force = mass x acceleration
• Weight = mass x gravity
• Acceleration = force/mass
• Hookes law: f=ke
• Pressure = force/area
• Moment = force x perpendicular distance to pivot
• Acm = cm or F1 x d1 = F2 x d2
• density = mass/volume
• Work done = force x distance
• Energy = work done
• Power = work done/time
• Output power = work done/time
• Efficiency = useful energy output/total energy input
• Wd = f x d = mgh/t
• Gravitational potential energy = mgh
• Kinetic energy = 1/2 mv^2
• Scalar is a quantity that has magnitude only, no direction.
• Vector is a quantity that has both magnitude and direction.
• The gradient of a distance time graph represents an objects speed
• The gradient of a speed tume graph represents an objects rate of change of speed
• The area between a speed time graph and the time axis is the distance moved
• The gradient of a displacement time graph represents an objects velocity
• The gradient of a velocity time graph represents an objects acceleration
• The area between a velocity time graph and the time axis represents the displacement
• Newton‘s first law: An object will remain at rest or continue at a constant velocity unless acted upon by a resultant force
• To demonstrate Newton's first law

  1. Use a linear air track and blower (to minimise friction)

  2. Use a glider and interrupt card

  3. Use two light gates

  4. Use a data logger and a computer
• Method


  1. Set the linear air track on a flat bench and adjust the feet on the air track to make sure that it is level

  2. Measure the length of the interrupt card and enter this in the data logger

  3. Connect up the light gates so that they measure the velocity of the glider at two points

  4. Give the glider a gentle push so that it passes through both light gates

  5. Confirm by looking at the results that the velocity does not change between the two positions of the light gate and so the glider is obeying Newton's first law of motion

  6. Repeat for other velocities and positions of the light gates
• Newton’s second law: The acceleration of an object is directly proportional to the resultant force acting on it
• Hooke’s law states that the extension of an object is directly proportional to the force applied, up to the limit of proportionality
• Centre of gravity is the point through which the entire weight of a body appears to act
• Equilibrium


  A state in which opposing forces or moments are balanced
• Neutral equilibrium


  • A state in which a slight displacement causes the object neither to move very far from its original position nor return to it (e.g. a ball sitting on a bench)
• Unstable equilibrium


  • A state in which a slight displacement causes the object to move a long way from its original position (e.g. a pencil balanced on its end)
• Stable equilibrium


  • A state in which a slight displacement causes the object to return to its original position (e.g. a traffic cone standing on its wide base)
• When an object is in equilibrium, the anticlockwise moment equals the clockwise moment