CP7/8 Forces

• Work Done = force x distance
• Power = work done / time taken
• Contact Forces = objects are touching e.g. push, pull
• Normal contact force = what happens to everything e.g. you on the floor
• Non-contact force = forces/objects don't touch e.g. gravity
• Vector = direction and magnitude
• Scalar = no direction
• Free body diagrams = represent the forces acting on an object e.g. plane (below)

  
• Scale diagrams can be used to find the resultant force

  
• Vector diagrams - resultant force = length of the line down the middle of the rectangle
• Energy transfers show useful vs. wasted energy

  
• Efficiency = (useful output)/(total input) x 100
• You can work out the resultant force using Pythagoras