 Momentum Exercise:

Problem:

For most people it is common sense to realize that if a car and bicycle hit you, traveling at the same speed, the car will do much more damage to you than the bike.  This is due to inertia.  Momentum is the measure of inertia in motion.  Therefore, momentum is influenced by the mass of an object and the velocity it is traveling (momentum = mv).  In this lab you will be testing the theory of momentum.

Materials:

1.                  Weights

2.                  Ring stand

3.                  Test tube holder

4.                  String

5.                  Block

6.                  Meter stick

Variables:

1)                  Mass

2)                  Velocity – Hint: if everything falls at the same rate of acceleration due to gravity, is it necessary to know what the velocity is?

Procedure:

1.                  Setup the experiment as shown in the picture above.

2.                  Hang the 100g weight from the test tube holder and position the block so that it is directly in front of the hanging weight.

3.                  Raise the weight to 5cm and release it so that it strikes the block directly.

a.       Repeat the experiment 3 times

b.      Repeat the step for the heights of 10cm & 20cm

c.       Repeat steps a & b using 200g & 500g weights.

4.                  Measure the distance the block traveled and record on your chart.

5.                  Calculate and record the averages of the distances traveled.

6.                  Graphing:

a.       Mass vs distance (Triple Bar Graph)

i.      X – Height,  Y – Distance

Data Tables:

Weight 1: 100g

 Height Trial 1 Trial 2 Trial 3 Average 5cm 10cm 20cm

Weight 2: 200g

 Height Trial 1 Trial 2 Trial 3 Average 5cm 10cm 20cm

Weight 3: 500g

 Height Trial 1 Trial 2 Trial 3 Average 5cm 10cm 20cm

Calculations:

1)      Calculate the velocity for each of the heights.  (Remember that all the weights accelerate the same due to gravity.)

(d = ½ g t2  or  t2 = d / (0.5 * 980 cm/s2               v = at

a. (d=5cm)

b. (d=10cm)

c. (d=20cm)

2)      Calculate the momentum for the different weights.  (mass * velocity) measured kg *cm/s or kg *m/s

 Weight 1 @5cm @10cm @20cm Weight 2 @5cm @10cm @20cm Weight 3 @5cm @10cm @20cm

Questions:

1)                  Using the results from the trials of 100g, predict the distances of the next to weights.

A)                Using the above information, predict how far the block at weights 2 & 3 should have traveled.

a.                   (Wt2/Wt1) x Dist@5cm for Wt1               _________cm

(Wt2/Wt1) x Dist@10cm for Wt1              _________cm

(Wt2/Wt1) x Dist@20cm for Wt1              _________cm

b.                  (Wt3/Wt1) x Dist@5cm for Wt1                _________cm

(Wt3/Wt1) x Dist@10cm for Wt1              _________cm

(Wt3/Wt1) x Dist@20cm for Wt1              _________cm

((predicted – measured)/predicted) * 100%

a.   Weight 2 @ 5cm                                                          _________%

Weight 2 @ 10cm                                                        _________%

Weight 2 @ 20cm                                                        _________%

b.   Weight 3 @ 5cm                                                          _________%

Weight 3 @ 10cm                                                        _________%

Weight 3 @ 20cm                                                        _________%

2)                  Name 3 conditions present that could have added to the error that you calculated.

a.

b.

c.

3)                  Conclusion:  On your own paper.

a.       Discuss the quality of your results. (State the accurate data that you were able to measure?)

b.      What conditions could have made your measurements inaccurate. (There are always conditions that make measurements, setup, and the procedure inaccurate.)

c.       What could have been done to improve the quality of your results?  (You can always improve.)