Michael Sturtevant
Period 6
10/21/98
Lab #4
Newtons Second Law
Purpose:
To verify Newtons second law
Theory:
The effect of an applied force is to cause the body to accelerate in the direction of the force. The acceleration is in direct proportion to the force and in inverse proportion to the mass of the body.
Procedure:
Supplies:
two 500kg weights
metric ruler
tickometer
car
wax tape
First gather all the supplies you need for this lab. Cut 2 strips of wax tape for your group. After that, tape the wax tape to the end of the car, and thread the other end all the way through the tickometer. Then tie a string to the front of the car and the other end of the string to a weight. Then assign people in your group to do specific jobs:
Then have them do their jobs. Have #1 turn on the tickometer and have #2 let go of the weight and make sure the car is going in a straight line so it doesn't mess the wax tape up. Then have #3 catch the car when the car drops off the edge of the table.
Then repeat those steps, but double the amount of weight at the end of the string.
After you have done that, take the 2 pieces of wax tape and divide them up into pieces, so that everyone in your lab group has a piece. Then each person has to count the number of dots made on the wax tape by the tickometer (start counting where the dots begin to be spaced far enough away to be counted easily). Mark off a line through every 2 dots until you get to the end of the tape. Those marked off sections are called intervals. You should have around 5 intervals. You use them to figure out the velocity of the car.
Data:
| Intervals | Ticks per
Interval | Length
(cm) | Velocity
(cm/tick) |
|---|
1
weight |
1 | 2 |
1 |
1 |
2 | 2 |
1 |
1 |
3 | 2 |
1 |
1 |
4 | 2 |
1 |
1 |
5 | 2 |
1 |
1 |
2
weights |
1 | 2 |
1 |
1 |
2 | 2 |
1 |
1 |
3 | 2 |
1 |
1 |
4 | 2 |
1 |
1 |
5 | 2 |
1 |
1 |
Calculations:
Results:
The acceleration of an object is in direct proportion to the force placed on that object. In this lab we proved this by measuring the slopes of 2 lines. One line was the best fit line for the acceleration of a car with one 500kg weight, and the other line was the acceleration of two 500kg weights. The slope of the line with one weight was almost half the slope of the other line. Thus proving that Newtons second law is true.
The 4.5% error was probally caused by the friction of the string on the table when it was pulling the car. Another possible cause of the 4.5% error was incorrect measurements of the best fit line.
Conclusion:
I feel I was very successful in this lab because I had a 4.5% error, which proved the law of acceleration to be true.
