2) 3.1 linear motion

• linear motion - movement of a body in a straight or curved line, where all parts move the same distance, in the same direction over the same time
• direct force - a force applied through the centre of mass resulting in linear motion
• centre of mass - the point at which a body is balanced in all directions. The point from which weight appears to act.
• linear motion results from a direct force being applied to a body, where the force is applied directly to the centre of a body's mass
• distance (m) - total length covered from start to finish positions
• displacement (m) - the shortest straight line route from start to finish positions
• speed (m/s) - the rate of change in distance calculated using; distance/time
• velocity (m/s) - the rate of change in displacement; calculated using displacement/time taken
• acceleration (m/s/s) - the rate of change in velocity; calculated using (final velocity-initial velocity)/time taken
• deceleration (m/s/s) - the rate of change is negative in velocity
• distance-time graphs:

  • time on x-axis
  • distance on y-axis
• distance-time graph

  diagram presenting = Stationary

  
• distance-time graph

  diagram presenting = acceleration

  
• distance-time graph

  diagram presenting = constant speed

  
• distance-time graph

  diagram presenting = deceleration

  
• A = rest

  B = acceleration

  C = constant velocity

  D = deceleration

  A) A

  B) B

  C) C

  D) D

  
• speed/time graphs

  • x-axis = time
  • y-axis = speed
• speed/time graph

  diagram presenting = constant speed

  
• speed/time graph

  diagram presenting = acceleration

  
• speed/time graph

  diagram presenting = deceleration

  
• velocity-time graph

  • x-axis = time
  • y-axis = velocity