Newton’s 2nd Law (F=ma)

Name : ______

Lab Partner(s): ______

Purpose:

To confirm Sir Issac Newton’s findings regarding accelerating masses using computerized data acquisition.

a) The acceleration is directly proportional to the applied force and

b) The acceleration is inversely proportional to the mass being accelerated

Materials:

lap top computer Logger Pro interface motion detector long track

cart (mass = 0.5kg) string masses with hooks

pulley that attaches to the track 0.5kg mass to rest on the cart.

Data:

Hanging Mass / Force (Newtons) / Accelerating Mass(kg) / Acceleration (m/s2) / F/m (m/s2) / % difference
g / Kg
50 / 0.050 / 0.49 / 0.550
100 / 0.100 / 0.98 / 0.600
50 / 0.050 / 0.49 / 1.050
150 / 0.150 / 1.47 / 1.150

Procedures and Calculations:

1. Practice starting the cart and catching it. Remember to keep your hands out of the way of the motion detector while data is being collected.

2. Record the hanging mass (in grams) in the table above. Convert that value to kg and record it.

3. The Force that causes the acceleration is the weight of the hanging mass. Compute this value and record it in the table.

4. The accelerating mass is the mass of the cart + the hanging mass. Compute this value and record it in the table.

5. Hit the collect button on the Logger Pro software and release the cart when you hear the motion detector start to click.

6. Find the acceleration from the graph or the data table and record your value in the table above.

7. Change the hanging mass and repeat steps 2 through 6.

8. Repeat steps 2 through 7 with the 0.5kg mass added to the cart.

9. Fill in the F/m column in the table for each of the 4 trials.

10. Compute the percent differences between the measured acceleration (from the computer) and the computed acceleration (F/m). Show the work for one of these computations below. Fill in the values in the data table.

Percent difference between 2 values is

Questions:

1. What does the slope of the velocity vs. time graph represent?

2. What does the slope of the distance vs. time graph represent?

3. Does your data support Newton’s second law? Explain your answer. Include the statement of the law in your explanation.

4. If you took your 4th trial and doubled the hanging mass, what would you predict as the new acceleration?

5. If you took your 4th trial and doubled the mass being accelerated, what would you predict as the new acceleration?

6. What time is it?