* Speed: The object is going faster or slower.
* Direction: The object is changing the direction it's moving in, even if its speed stays the same.
Here's a breakdown:
* Acceleration is a change in velocity.
* Velocity is a combination of speed and direction.
Examples of acceleration:
* A car speeding up: The car's speed is increasing, so it's accelerating.
* A car slowing down: The car's speed is decreasing, so it's also accelerating (even though it's slowing down!).
* A car turning: The car's direction is changing, even if its speed stays the same, so it's accelerating.
* A ball thrown in the air: The ball's speed changes as it goes up and then down, and it's also changing direction, so it's constantly accelerating.
What causes acceleration?
Acceleration is caused by a force. The bigger the force, the bigger the acceleration. This is described by Newton's second law of motion:
* Force = Mass x Acceleration
In other words:
* If you push a heavy object (high mass), it will accelerate less than if you push a lighter object (low mass) with the same force.
* If you push harder (higher force), an object will accelerate more than if you push softer (lower force).
