* Acceleration is the rate of change of velocity. This means that if an object is accelerating, its velocity is changing.
* Direction matters: Acceleration can change the speed of an object (how fast it's moving) or its direction of motion, or both.
* Constant acceleration: If an object experiences constant acceleration, its velocity will change at a steady rate.
* Variable acceleration: If an object experiences variable acceleration, its velocity will change at a varying rate.
Examples:
* Car speeding up: A car accelerating from rest experiences an increase in velocity.
* Car braking: A car braking to a stop experiences a decrease in velocity.
* Ball thrown upwards: A ball thrown upwards experiences deceleration (negative acceleration) due to gravity, causing its velocity to decrease until it momentarily stops at its highest point. Then, as it falls back down, the acceleration due to gravity causes its velocity to increase.
* Object moving in a circle: An object moving in a circle at a constant speed still has acceleration because its direction is constantly changing. This is called centripetal acceleration.
Key points:
* Zero acceleration means constant velocity. If an object has zero acceleration, its velocity remains the same (both speed and direction).
* Acceleration can be positive or negative. Positive acceleration means an increase in velocity, while negative acceleration (also known as deceleration) means a decrease in velocity.
In essence, acceleration is the "push" or "pull" that changes an object's velocity. It's the fundamental concept that links motion and force in physics.
