Momentum and Moment (pg 12-14) T.S

• Formula for momentum: $p=$$mv$
• The greater the mass of an object and the greater its velocity, the more momentum the object has
• Momentum is a vector quantity - it has size and direction
• Momentum is conserved when no external forces act. Momentum before = momentum after
• When a force acts on an object, it causes a change in momentum
• Formula for force with change in momentum: $F=$$(mv-mu)/t$
• Formula for change in momentum: force = change in momentum / time
• A larger force means a faster change of momentum
• Cars are designed to slow people down over a longer time when they crash - the longer is takes for a change in momentum, the smaller the force
• A moment is the turning effect of a force
• Formula for moment: Moment (Nm) = Force (N) * Perpendicular distance between line of action and pivot (m)
• The centre of gravity hangs directly below the point of suspension
• A freely suspended object will swing until its centre of gravity is vertically below the point of suspension
• For simple shapes, you can find the centre of gravity by looking for lines of symmetry
• The principle of moment says that if an object is balanced then:

  Total Anticlockwise Moments = Total Clockwise Moments
• If a heavy object is placed on a rod, the support closest to the object will provide a larger force
• If the anticlockwise moments do not equal the clockwise moments, there will be a resultant moment. (So the object will turn)