Speed and Acceleration for Kids: How Fast and How It Changes (Grades 6 to 8 Science)

Hi, I'm Luna from DoodleBeez. Cars, runners and rockets all move, but how do we describe that motion? Today we will learn about speed, velocity and acceleration.

Speed tells how far something travels in a certain amount of time. To find speed, divide the distance by the time. Speed equals distance divided by time.

Let's try one. A runner goes one hundred meters in twenty seconds. One hundred divided by twenty is five. So the runner's speed is five meters per second.

Velocity is speed in a given direction. Fifty miles per hour is a speed. Fifty miles per hour heading north is a velocity. Two cars can have the same speed but different velocities.

Acceleration is a change in velocity. Speeding up is acceleration. Slowing down is acceleration too. Even turning a corner at a steady speed is acceleration, because the direction changes.

What causes acceleration? An unbalanced force. A bigger force makes an object accelerate more. But a heavier object needs more force to get the same acceleration. That is why pushing a truck is harder than pushing a bike.

Now it's your turn. A bike travels sixty meters in ten seconds. What is its speed? Pause and try. Sixty divided by ten is six. The speed is six meters per second.

Great job! Remember, speed is distance divided by time, velocity adds direction, and acceleration is any change in velocity. Practice speed and acceleration in the Science Lab at doodlebeez.com. See you next time!