Practice question · Multiple choice
An object can have positive velocity and negative acceleration at the same moment. Why does that combination not mean it is moving backwards?
Hints
- A car travelling forward and braking: what is the sign of each quantity?
- Ask what acceleration is the rate of change OF.
Show the answer
A. Because velocity gives direction and acceleration gives its change.
Why
The two answer different questions: velocity is which way and how fast, acceleration is how that is being altered. Positive velocity with negative acceleration is a car moving forward with the brakes on. The commonest error in kinematics is reading acceleration as 'speeding up', a thrown ball has constant downward acceleration going up, at the top, and coming down.
Practise Kinematics and the Language of Motion
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