Acceleration is a change in speed and/or direction
Explanation:
The acceleration of an object is defined as the rate of change of velocity, mathematically:
where
is the change in velocity
is the time taken for the velocity of the object to change
We notice that velocity is a vector quantity, so it consists of:
- A magnitude, which is called speed
- A direction
Since acceleration is the rate of change in velocity, this means that the acceleration is non-zero whenever is non-zero, which means that either the speed AND/OR the direction of the velocity is changing.
For instance:
- For an object which is speeding up along a straight line, the speed is changing but the direction is not --> still, the object is accelerating
- For an object moving in a uniform circular motion, the speed is constant while the direction is changing --> still, the object is accelerating
So the correct answer is
a change in speed and/or direction
Learn more about acceleration:
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