# Lesson 18 Motion of a Fan Car.

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Lesson 18 Motion of a Fan Car

Getting Started What does the term averages speed mean?
How do you calculate average speed? A car travels 100 meters in 2 seconds. What is its speed? A jogger runs 50 meters in 25 seconds. What is the jogger’s speed?

18.1 Investigating the Motion of the Fan Car
Predict the motion of the fan car if you push it without turning the fan on. Push the fan car. Use a steady push. Record your observations of its motion after you release it. Push the car two more times using pushes of different strengths. What differences do you see in the motion of the car when you push with different forces?

When you pushed on the car, your hand exerted a force on it
When you pushed on the car, your hand exerted a force on it. List in your science notebook any other forces that were acting on the car when you pushed it. What forces acted on the car after you released it?

Turn the Car on and Hold in Place
Answer the following questions without letting the car go: What do you feel when you simply hold the car with the fan running? In what direction does the fan move the air? In what direction does the fan car want to move? * Release the car, observe its motion. Record your observations in your notebook.

Inquiry 18.2 Measuring the Fan Car’s Speed
What is the equation for calculating speed?

Measuring the Fan Car’s Speed
Distance Interval Position Time Trial 1 seconds Time Trial 2 Time Trial 3 Average Average Speed m/s 1 2 3 4 5

Data Questions What patterns do you observe in your speed data?
What are the forces on the fan car when the car is moving with the fan turned off and when it is moving with the fan turned on? What evidence do you have to support your answer?

Is the force of the fan constant or changing as the car moves along
Is the force of the fan constant or changing as the car moves along? Give reasons for your answer. What is the effect of the force of the fan on the speed of the car? Give evidence. What can you conclude about the effect of a constant fan force on the motion of the car?

6. What energy changes take place as the car moves along with the fan running?