Pages Covered - 26-29

• Just as we can represent the motion of a moving object by a distance–time graph, we can also represent it by a speed–time graph. A speed–time graph shows how the object’s speed changes as it moves.

• Types Of Slopes

  • The steeper the slope, the greater the acceleration

  • A negative slope means a deceleration (slowing down)

  • A horizontal graph (slope = 0) means a constant speed.

• Types Of Graphs

  • Speed–time graphs can show us a lot about an object’s movement.

    
    

• A : Sloping upwards, so the speed increases and the train is accelerating

• B : The slope is moving in a constant speed at the graph

• C : Sloping downwards, so the speed decreases and the train is decelerating

• D : Speed has decreased to zero and the train is stationary.

• Finding Distance Through Graphs

  • Formula : Distance = Area under speed–Time graph

• Example

  • You set off down a steep ski slope. Your initial speed is 0 m/s. After 10 s you are travelling at 30 m/s. Calculate The distance

    
    

• Area of a triangle = 12 × base × height

• = 12 × 10 s × 30m/s

• = 150 m