12/26/2010

Homeschool Science - Teach Speed, Velocity, and Acceleration

A simple, small toy car can be used to illustrate these concepts. In addition, use real-life examples before using mechanical examples.

Speed
Show the toy car moving across a table. Ask what speed is.

Give the formula that speed is distance divided by time. Let the student make up examples of speed based on trips they have taken in the car.

The formula is Rate = Distance/Time. Use the formula on the examples they made up.

Velocity
Velocity is speed in a given direction.
Show your toy car moving in one direction. Then you turn the car around and head back in the opposite direction towards where you started. The speed may be the same. But the velocity is different.

How would you measure velocity? The total distance from the starting point to the ending point divided by the time elapsed. It is not the same as the total distance the object moved.

In another example, show the car moving in one direction, then have it turn at an angle and keep moving. The ending distance from the point started to the point ended would be different than the total distance traveled.

Velocity is stated as a distance in a given direction using the compass.

Acceleration
Students are usually familiar with the concept of acceleration, or speeding up. It is defined as the change in speed over time.

In physics, meters per second per second is most commonly used. Again, the simple toy car can easily illustrate this.

Many cars are about 5 meters long, so let the student create a paper scale where the length of your toy car is 5 meters. Make a scale the length of at least six cars.

In one second your car accelerates from standing still to five meters per second. The next second the car is moving ten meters per second. Then the car is moving fifteen meters per second. What is the rate of acceleration?

The simple formula is Change in Speed divided by Time. Since the car moved 15 meters in 3 seconds, it is accelerating at a rate of 5 meters per second per second.

Let the student make up additional examples of their own. Then use the formula to solve their own examples.

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