motion

• speed is defined as the distance travelled per second and is measured in metres per second. speed is a scalar quantity
• the velocity of an object is defined as the displacement travelled per second and is measured in metres per second. velocity is a vector quantity
• cos to go across
• sine to climb
• acceleration is defined as the change in velocity per second
• starts from rest means initial speed = 0
• comes to rest means final speed = 0
• the gradient of a velocity-time graph gives acceleration
• the area under a velocity-time graph gives displacement
• the area under an acceleration-time graph indicates the change in velocity
• the gradient of a displacement-time graph gives the velocity of the object
• equation 1 of motion: $v=$$u\ +$$\ at$
• equation 2 of motion: $s=$$ut\ +$$\ \frac{1}{2}at^2$
• equation 3 of motion: $v^2=$$\ u^2\ +$$\ 2as$
• when an object decelerates, its velocity decreases
• an acceleration-time graph is always a straight line
• if an acceleration- time graph is on the x-axis, constant velocity
• if an acceleration-time graph is above the x-axis, positive accceleration
• if an acceleration-time graph is below the x-axis, negative acceleration
• object dropped


  a=9.8ms-2

  u=0ms-1
• object thrown upwards

  a=-9.8ms-2

  v=0ms-1
• explain what is meant by an acceleration of 0.32ms-2

  the velocity increases by 0.32ms-1 per second