Physics Unit 1

• 6 SI Units= kg, N, m, s, m, c
• Homogeneity: the quality or state of being all the same or all of the same kind
• Scalar- Only measures magnitude
• Vector- A quantity that has both magnitude and direction.
• density: the degree of compactness of a substance
• torque: a force that tends to cause rotation
• moment: product of force and the perpendicular distance from the point to the line of action of the force
• How is an object in equilibrium?


  the resultant force is zero and resultant moment is zero
• principle of moments: total clockwise moment = total anticlockwise moment
• Centre of Gravity: Point where the entire weight can be considered to act on
• Displacement


  Distance and direction of an object's change in position from the starting point.
• mean speed


  total distance travelled / total time taken
• instantaneous speed


  rate of change of distance
• mean velocity


  total displacement/total time taken
• instantaneous velocity


  rate of change of displacement
• mean acceleration


  Change in velocity / time taken
• instantaneous acceleration


  rate of change of velocity
• how to calculate velocity on distance time graph

  gradient

  
• How to calculate acceleration and area in a velocity time graph


  gradient is acceleration

  area is dsplacement

  
• 4 xuvat equations


  v=u+at

  x=1/2(u+v)t

  x=ut+1/2at^

  v^=u^+2ax
• terminal velocity


  the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity
• projectiles


  does not affect horizontal motion but will accelerate vertically downwards
• Force

  A push or a pull exerted on an object and changes the velocity of a body
• Newton's Third Law

  If body A exerts a force on body B, then body B will exert an equal and opposite force on body A.
• free body diagram


  a diagram showing all the forces acting on an object

  
• Newtons 2nd law

  force is equal to the rate of change of momentum
• conservation of momentum

  The total momentum before a collision is equal to the total momentum after a collision
• inelastic collision

  a type of collision in which the kinetic energy after the collision is less than the kinetic energy before the collision
• force is equal to the rate of change of momentum


  F=deltap/deltat
• work done


  energy transferred to or from an object via the application of force along a displacement
• work done


  equal to the amount of energy transferred
• gravitational potential energy


  e=mgh
• kinetic energy formula


  1/2mv^2
• Power equation


  P=W/t
• conservation of energy


  energy cannot be created or destroyed, only transferred
• elastic potential energy


  energy of an object due to it being deformed by a force
• elastic potential energy formula


  1/2kx^2
• efficiency


  The percentage of the input work that is converted to output work
• efficiency formula


  Work output/work input x 100%
• hookes law


  tension in a spring or wire is proportional to its extension from its natural length