Lab 7, Inelastic Collisions
03/19/2000Courtesy of Chiung-Yuan Lin and Benli Young
1. Prepare and weigh the gliders and all masses:
| Object |
Mass, Unit:( ) |
|||||||||||
|
Glider with pin |
|
|||||||||||
|
Glider with plug |
|
|||||||||||
|
Masses |
|
|
|
|
|
|
||||||
2. Set up timing photo-gates:
The length of Glider should be the total length which the photo-gate can detect.
| Item |
Glider with pin |
Glider with plug |
Average of two Gliders |
|
Length, Unit:( ) |
|
|
|
3. Make measurements: (Just fill in the data)
The positive velocities are measured to the right
You do all three cases and choose only one case to complete the whole row. Your sample calculation is not required here.
|
m1 (kg) |
m2 (kg) |
V1i (m/s) |
V2i (m/s) |
Vf (m/s) |
Pi (kg-m/s) |
Pf (kg-m/s) |
D P(kg-m/s) |
Ki (Joul) |
Kf (Joul) |
D K(Joul) |
(DK / Ki)´ 100% | (DK / Ki)´ 100% |
| % | % | |||||||||||
| % | % | |||||||||||
| % | % |
You do all three cases, choose only one case to go through it to (D K / Ki )´ 100% and write down your sample calculation.
|
m1 (kg) |
m2 (kg) |
V1i (m/s) |
V2i (m/s) |
Vf (m/s) |
Pi (kg-m/s) |
Pf (kg-m/s) |
D P(kg-m/s) |
Ki (Joul) |
Kf (Joul) |
D K(Joul) |
(DK / Ki )´ 100% |
|
|
|
|
|
|
|
|
|
|
% |
||
|
|
|
|
|
|
|
|
|
|
% |
||
|
|
|
|
|
|
|
|
|
|
|
|
% |
4. Answer the Additional Question I, (2 point)
Starting from the two equations on Page 43, derive an expression of DK only in terms of m1, m2, V1i, V2i. Then simplify your expression to prove that DK ³ 0 for any initial velocities. Your mathematical work stands one point. (0.5 points for your final answer) How can we make DK = 0? (0.5 points) Is it possible to perform the specific situation today? Why?
Hint: m1V1i+m2V2i = (m1+m2)Vf, (a + b)2 = a2 + 2ab + b2, and (a - b)2 = a2 - 2ab + b2
II. Other inelastic collisions
1. m (kg) Vi (m/s) Vf (m/s) Ki (Joul) Kf (Joul) D (Joul) % % %
(DK/ Ki )x100%
2. Plot Graph "D K versus Ki".
3. Answer Question 2 on page 43: Is a constant fraction of energy lost, or is a fixed amount of energy lost?
Hint: Do not answer this question with a simple "YES" or "NO" or you loss 1 point. Use your Graph "DK versus Ki" to answer this question.
Below is a sample when performing collisions with the “wax” glider initially at rest.
|v1i| = 0.638(m/sec), |v2i| = 0.000(m/sec), |vf| = 0.303(m/sec)
| Special option values - "collision Timer" Mode | ||
|
Row |
velocity |
velocity |
|
# |
(m/sec) |
(m/sec) |
|
1 |
0.6376 |
0.3025 |
|
2 |
Error |
0.2972 |
Carefully read the following remark when performing collisions by launching both gliders.
| Special option values - "collision Timer" Mode | ||
|
Row |
velocity |
velocity |
|
# |
(m/sec) |
(m/sec) |
|
1 |
0.5470 |
0.3862 |
Below is a sample when vf goes back and forth.
|v1i| = 0.547(m/sec), |v2i| = 0.386(m/sec), |vf| = 0(m/sec)
Below is a sample when vf goes fast enough.
|v1i| = 0.391(m/sec), |v2i| = 0.468(m/sec), |vf| = 0.0938(m/sec)
| Special option values - "collision Timer" Mode | ||
|
Row |
velocity |
velocity |
|
# |
(m/sec) |
(m/sec) |
|
1 |
0.3909 |
0.4677 |
|
2 |
Error |
0.09375 |
|
3 |
Error |
0.09110 |
Below is a sample when vf goes too slow.
|v1i| = 0.549(m/sec), |v2i| = 0.468(m/sec), |vf| = 0.0148(m/sec)
| Special option values - "collision Timer" Mode | ||
|
Row |
velocity |
velocity |
|
# |
(m/sec) |
(m/sec) |
|
1 |
0.5489 |
0.4678 |
|
2 |
Error |
0.01483 |