Area under a velocity-time graph gives distance travelled
2 marks · EasyExplain why the area under a velocity–time graph is sometimes a triangle and sometimes a rectangle. Give an example of each case.
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Triangle: for constant acceleration (velocity starting from zero or changing); Rectangle: for constant velocity (velocity stays the same)
Must show: Correct explanation of triangle/rectangle, Relevant example for each
Common mistakes: Confusing constant velocity with acceleration
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Marking points
B1 · 1 mark · States triangle area is for accelerating motion (sloping straight line); rectangle area is for constant velocity (horizontal line).
B2 · 1 mark · Provides an example of each (e.g. starting from rest: triangle; steady speed: rectangle).
Worked solution
Triangle: When the object starts from rest or its speed changes at a steady rate (constant acceleration), as in a ball rolling down a ramp. Rectangle: When the object moves at constant velocity, such as a car driving at steady speed.