Acceleration

    • Acceleration is the rate of change of velocity. So in other words, acceleration tells you how quickly the velocity is increasing or decreasing. An acceleration of indicates that the velocity is increasing by

    • in the positive direction every second.

    • Gravity near the Earth pulls an object downwards toward the surface of the Earth with an acceleration of . In the absence of air resistance, all objects will fall with the same acceleration. The letter

    • is used as the symbol for the acceleration of gravity.

        • When talking about an object's acceleration, whether it is due to gravity or not, the acceleration of gravity is sometimes used as a unit of measurement where . So an object accelerating at 2g's is accelerating at

        • or

    • Deceleration is the term used when an object’s speed (i.e. magnitude of its velocity) is decreasing due to acceleration in the opposite direction of its velocity.

In science, acceleration refers to increasing speed, decreasing speed, and changing direction.

Increasing Speed-

Is when an object gains momentum or it accelerates.

"Increasing the Speed of a Ball"

Increasing Speed

In this picture you can see that the football player is throwing the football. He is increasing the speed of the football as a reaction to him throwing it.

Decreasing Speed-

Is when an object loses momentum or decelerates.

"Decreasing the Speed of a Ball"

Decreasing Speed

This picture shows a girl catching a softball and in doing so she is decreasing the speed of the softball.

Changing Direction-

Is when an object totally changes its coarse of travel.

"Velocity"

In this picture you can see that the car is changing it's direction.

What is Acceleration?

Acceleration means "the process of speeding up". Acceleration is the rate at which velocity changes. ​ Acceleration is specified by a number and a direction. It is usually measured in units such as meters per second per second, or meters per second squared. For a cool activity to show acceleration, go to http://library.thinkquest.org/27948/accel.html. ​The three ways an object can accelerate are increasing speed, decreasing speed, and changing direction. Whenever and object's speed increases, the object accelerates. For example, a softball accelerates when a pitcher throws it, and when again when a ball hits it.

When an object decreases speed it decelerates or negatively accelerates. For example, when a softball is caught by a fielders it loses all its acceleration. When an object changes direction, it gains speed. For example, when a softball thrown by the pitcher is hit by the batter it changes direction and gains speed.

"Changing the Direction of a Ball"

Changing Direction

In this picture you can see that when the soccer player kicks the soccer ball it changes from going towards him to going away from him.

Calculating Acceleration-

To determine the acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time.

Final Speed- Initial Speed = Acceleration

Time

Velocity

Velocity has to do with acceleration because when you change direction you are changing your velocity or when you are speeding up or slowing down you are also changing your direction.

This man is decelerating after he passes the finish line