Forces

• State that forces change the shape, speed or the direction of moving objects.
• forces are measured with a force meter.
• the size of a force is measured in newtons (N).
• friction is a force that acts to resist movement.
• friction with the air is called air resistance, or drag.
• air resistance can be reduced by streamlining.
• What are moments?


  If an object is balanced the total clockwise moment equals the total anticlockwise moment
• Bad uses of friction:


  Drag, hovercrafts, carpet burn
• Good uses of friction:


  Tyres, shoes, brakes
• What does friction always try to do?

  It always tries to slow down an object
• What 2 main factors affect friction?

  1. Speed of the object. 2. Surface area in contact
• What is friction?


  Friction is a force
• What is the formula to find weight?

  Weight = Mass x Gravity. (W=MxG) (W=MG)
• What does mass tell us?

  It tells us how much there is of an object
• What is mass measured in?

  kg (kilograms)
• What is weight not the same as?

  Weight is not the same as mass
• What is weight measured in?

  Newtons (N)
• What is weight?

  It is a force caused by gravity
• What 2 things will happen then an object is under unbalanced forces?

  - accelerate (get faster). - decelerate (get slower)
• What does an unbalanced force mean?

  An unbalanced force means that the forces do not cancel out
• What 2 things can happen o if there are balanced forces on an object?

  - moving at a constant speed. - not moving at all
• What does a balanced force mean?

  A balanced force means that 2 or more forces are acting on an object and are cancelling out
• What is used to measure exerted force?

  Newtonmetre
• What is force measured in?

  Newtons (N)
• What 3 things can forces do?

  Change: -speed, -direction, -shape
• What is a force?

  It is an interaction between 2 objects.