rate at which velocity changes acceleration: rate at which velocity changes

Scalar Vector

Acceleration Quick Reference  

Velocity-time Graphs A graph that plots an object’s velocity versus the time. The rate at which an object’s velocity is changing is called acceleration and can be found by calculating the slope of the velocity-time graph.

Example Graph:

Facts about acceleration: Acceleration is the change in velocity divided by the time it takes to make that change. It is possible to have positive or negative acceleration as well as acceleration equal to zero. Acceleration is a vector quantity with the SI unit of m/s2, pronounced “meters per second squared.” A change in direction will cause a change in acceleration.

Example Problem 1 Describe the motion of the object represented in this graph:

From 0 to 5.0 s: From 5.0 to 10.0s: From 10.0 to 15.0s: Speeds up from rest at a constant rate From 5.0 to 10.0s: Remains at a constant speed of 30.0m/s From 10.0 to 15.0s: Decreases in speed from 30 to 20m/s From 15.0 to 20.0s: Remains at a constant speed of 20m/s From 20.0 to 25.0s: Comes to a stop

V A T

Average Acceleration Total Change in Velocity Total Change in Time

Instantaneous Acceleration Change in Velocity Change in Time

Example Problem 2 Find the uniform acceleration that causes a car’s velocity to change from 32 m/s to 96 m/s in an 8.0-s period.

Notice how every number in the problem is represented in the picture! Ex Prob 2 picture t = 8.0s a = ? Notice how every number in the problem is represented in the picture! vi = 32m/s vf = 96m/s

Acceleration due to gravity The acceleration caused by the force which gravity exerts on a falling object Acceleration due to gravity = 9.8 m/s²