A car accelerates from rest. The graph shows the variation of the momentum of the car with time.
What is the meaning of the gradient of the graph at a particular time?
A the kinetic energy of the car
B the rate of change of kinetic energy of the car
C the resultant force on the car
D the velocity of the car
ANSWER: C
The Physics behind the answer:
- The gradient is the steepness of a line that is measured by dividing the change along y-axis by the change along the x-axis.
- In the case of the above graph, gradient is determined by dividing a Δ momentum by a corresponding Δ time.
- This Δ momentum per Δ time is our definition of force.
Other Physics concepts related to the question:
- Since the graph is a curve, there is a need for us to draw a tangent line at the time value in question, if we are to calculate actual values. The [resultant] force on the object at that time is the gradient of the tangent line.
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