Acceleration
How fast your velocity changes. Speeding up, slowing down and turning all count as acceleration.
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Analogy
The gas pedal, the brake and the steering wheel all cause acceleration.
Example
a = change in v / timea = (27 - 0) m/s / 9 sa = 3 m/s^2
In practice
A car goes from 0 to 27 m/s in 9 s. Its acceleration is 3 m/s squared.
Practice
Flashcards
- What is the unit of acceleration in SI?Metres per second squared (m/s^2).
Interview questions
- Explain why a car going round a bend at steady speed is still accelerating.
- Acceleration is a change in velocity
- Direction changes even if speed does not
- Acceleration points toward the centre of the bend
Questions people ask
Can an object have zero velocity and non-zero acceleration?
Yes. A ball thrown upward stops for an instant at its highest point, but gravity is still pulling it. Its velocity is zero there while its acceleration is still 9.8 m/s^2 downward. If acceleration were zero, the ball would stay at the top forever.
What does negative acceleration mean?
Negative acceleration means the acceleration points in the negative direction you chose. It does not always mean slowing down. A car moving in the negative direction and speeding up has negative acceleration. Slowing down happens when velocity and acceleration point in opposite directions.