Background: How long does it take a car to move 200 centimeters? 

We all have a good idea that if it takes a smaller period of time to move 50 centimeters, the car must be moving faster. But how do we measure the speed of a toy car? In your own car, it is easy because engineers have designed a speedometer that automatically tells you how fast your car is moving. A common unit for speed is miles per hour. From this it is easy to figure out the formula that we have to use to calculate the speed of a toy car. Miles is a unit to measure distance. Hour is a unit to measure time. The word PER stands for division. So, if Miles Per Hour = Miles / Hour we can replace miles with distance and hour with time and we get the following formula: 

speed = distance / time  

Purpose: The purpose of this experiment is to determine the average speed of a toy car.

Hypothesis: If the distance and time is measured then the average speed can be determined from a distance vs. time graph because the slope of the line is speed. 

Variables:

IV: Time (s)

DV: Distance (s)

Materials: Toy Car, Tape, Stopwatch, Meter Stick 

Procedure: 

1. Mark off the following distances on the floor with tape: 0 meters, 50 cm, 100 cm, 150 cm and 200 cm.

2. Wind up your car and set it before the 0 m mark.  Release the car. 

3. When the front of the car reaches the 0 meter mark, start your timer. Then, stop the timer when the front of the car reaches the 50-cm mark. Record the time in the table on the back. 

4. Repeat this procedure for 2 more trials. 

5. Calculate the average time and record it in the table. (Add up time trials for that distance and divide by 3.) 

6. Calculate the average speed and record it in the table. (See speed formula above.) 

7. Repeat steps 1-6 for the 100-cm mark and 200-cm mark.

Pre-Lab Assignment: Answer the following questions in complete sentences and thoughts using the information in the background to support your answers.

1. What is the difference between instantaneous speed and average speed?

Instantaneous speed is the speed…..and average speed is……

2. How will the instantaneous speed of the car be determined in this lab? Explain your answer.

The instantaneous speed will be determined by……

3. How will  the average speed of the car be determined in this lab? Explain your answer.

The average speed will be determined by…

4. What is the difference between speed and velocity?

The difference between speed and velocity is that speed is ……however, velocity is……

5. In this lab we are calculating the speed of a toy car? Are we able to determine the velocity of the toy car as well?  If so, how can we figure it out?

Yes, we can determine the velocity by….

6. If you record the time it takes for the car to move 50 centimeters and then record the time it takes to move 150 centimeters, will there be a difference in the speed of the car between the two runs? Explain your prediction.

The answer to this question depends on the speed of the car…….