Lab 8: Energy and Momentum The conservation principles are some of the most powe
ID: 306091 • Letter: L
Question
Lab 8: Energy and Momentum
The conservation principles are some of the most powerful concepts to have developed in physics. In this lab, we will explore conservation of momentum and conservation of energy.
Data Collection for Part 2: Rolling objects on a ramp.
1. Record the mass and radius of each shape.
2. Adjust the rods’ spacing so that they guide the sphere down the track with minimum interference. Space the photogates far apart, but leave yourself enough room at the far ends of the track to release and catch the ball.
3. Record the height of each photogate above the table. Record the separation of the photogates.
4. Adjust each photogate to the same height, relative to the track! Do this step carefully.
5. In DataStudio, click ports 1 and 2 to choose the photogates. Display a table of “Time between any gates, Ch 2 (s)”. Click start and do a trial run: roll the ball down through both photogates. Make sure the table gives you one time value that seems reasonable. (If it does not seem correct, ask for help.)
6. It is important that your object starts from rest right before the first photogate. Hold the ball at the top of the track so that the photogate is blocked (and the red light is on). Roll the ball back just until the red light goes off. This is your starting position.
7. Click start, let the ball run down the track through both gates, and catch the ball. Record the time.
8. Do two more trials with the metal ball.
9. Do three trials with the cylinder. If the cylinder doesn’t roll freely, adjust the rods and re-try the run.
10. Clean up; leave the lab equipment as you found it.
Lab Data
Mass of cylinder = 0.11kg
Diameter = 4.7mm = (0.0047m)
Radius = 0.00235m
Mass of Silver ball = 0.225kg
Diameter of silver ball = 5.4mm = (0.0054m)
Radius of silver ball = 0.0027m
Right photogate length = 0.117m
Left photogate length = 0.117m
Separation of photogate = 1.513m
Cylinder
Time started (s)
Time stopped (s)
Trial 1
1.23
1.83
Trial 2
1.23
1.81
Trial3
1.28
1.81
Silver ball
Time started (s)
Time ended (s)
Trial 1
1.05
1.67
Trial 2
1.15
1.62
Trial3
1.04
1.69
Part 2 Analysis (PLEASE THIS IS WHERE I NEED HELP)
Organize all your recorded data into tables. Start a new table for your results.
For each shape, determine the following quantities one time, using the average times.
?t average f) pxf k) % difference between pi and pf
I value g) Lf l) % difference between Li and Lf
ax (via kinematic equation) h) UG,i (set UG,f =0 at bottom gate) m) % difference between Etotal,i and Etotal,f
vxf (via kinematic equation) i) Kf
?f j) Krot,f
A full lab report IS NOT required. Hand in:
Your well-labeled data tables and result tables.
Your typed responses to the following:
1. Briefly describe the concept of conservation. Briefly describe when each of these types of conservation are valid: conservation of energy, conservation of kinetic energy, conservation of momentum, and conservation of angular momentum.
PART 2
2. Discuss if your two shapes obeyed conservation of momentum, conservation of angular momentum, and conservation of energy. (Re-state all values in your discussion that you allude to.) Discuss if each of these should have been conserved.
3. Describe if you think your experiment was accurate and/or precise. Back up your statements.
Describe a couple sources of uncertainty that would have affected your results but could not be eliminated from the lab. For each, mention how it would have affected your results, accuracy, and/or precision.
Lab 8: Energy and Momentum
The conservation principles are some of the most powerful concepts to have developed in physics. In this lab, we will explore conservation of momentum and conservation of energy.
Data Collection for Part 2: Rolling objects on a ramp.
1. Record the mass and radius of each shape.
2. Adjust the rods’ spacing so that they guide the sphere down the track with minimum interference. Space the photogates far apart, but leave yourself enough room at the far ends of the track to release and catch the ball.
3. Record the height of each photogate above the table. Record the separation of the photogates.
4. Adjust each photogate to the same height, relative to the track! Do this step carefully.
5. In DataStudio, click ports 1 and 2 to choose the photogates. Display a table of “Time between any gates, Ch 2 (s)”. Click start and do a trial run: roll the ball down through both photogates. Make sure the table gives you one time value that seems reasonable. (If it does not seem correct, ask for help.)
6. It is important that your object starts from rest right before the first photogate. Hold the ball at the top of the track so that the photogate is blocked (and the red light is on). Roll the ball back just until the red light goes off. This is your starting position.
7. Click start, let the ball run down the track through both gates, and catch the ball. Record the time.
8. Do two more trials with the metal ball.
9. Do three trials with the cylinder. If the cylinder doesn’t roll freely, adjust the rods and re-try the run.
10. Clean up; leave the lab equipment as you found it.
Lab Data
Mass of cylinder = 0.11kg
Diameter = 4.7mm = (0.0047m)
Radius = 0.00235m
Mass of Silver ball = 0.225kg
Diameter of silver ball = 5.4mm = (0.0054m)
Radius of silver ball = 0.0027m
Right photogate length = 0.117m
Left photogate length = 0.117m
Separation of photogate = 1.513m
Cylinder
Time started (s)
Time stopped (s)
Trial 1
1.23
1.83
Trial 2
1.23
1.81
Trial3
1.28
1.81
Silver ball
Time started (s)
Time ended (s)
Trial 1
1.05
1.67
Trial 2
1.15
1.62
Trial3
1.04
1.69
Part 2 Analysis (PLEASE THIS IS WHERE I NEED HELP)
Organize all your recorded data into tables. Start a new table for your results.
For each shape, determine the following quantities one time, using the average times.
?t average f) pxf k) % difference between pi and pf
I value g) Lf l) % difference between Li and Lf
ax (via kinematic equation) h) UG,i (set UG,f =0 at bottom gate) m) % difference between Etotal,i and Etotal,f
vxf (via kinematic equation) i) Kf
?f j) Krot,f
A full lab report IS NOT required. Hand in:
Your well-labeled data tables and result tables.
Your typed responses to the following:
1. Briefly describe the concept of conservation. Briefly describe when each of these types of conservation are valid: conservation of energy, conservation of kinetic energy, conservation of momentum, and conservation of angular momentum.
PART 2
2. Discuss if your two shapes obeyed conservation of momentum, conservation of angular momentum, and conservation of energy. (Re-state all values in your discussion that you allude to.) Discuss if each of these should have been conserved.
3. Describe if you think your experiment was accurate and/or precise. Back up your statements.
Describe a couple sources of uncertainty that would have affected your results but could not be eliminated from the lab. For each, mention how it would have affected your results, accuracy, and/or precision.
Explanation / Answer
I am considering that the time started is the time when the ball or the cylinder passes through first photogate and time stopped is the time when it reached the second photogate.
Trial 1
Since the object starts from rest initial velocity u=0, acceleration a=g,let g=10m/s
v= u + gt
final velocity v= g x 0.57
vf =5.7 m/s
v=w x r w= angular velocity , r = radius of cylinder
wf = 5.7/0.00235 = 2425.5 s-1
initial momentum =0
final momentum = pf = mv = 0.11 x 5.7 = 0.627 Kg m/s
final angular momentum Lf = I w where I is moment of inertial
Moment of inertia of cylinder about its axis I = 1/2 mr2
I= 3.037 x 10-7 Kg m2
Lf = I wf = 3.037 x 10-7 x 2425.5 =7.37 x 10-4 Kg m2 s-1
Kinetic energy final Kf = 1/2 mv2
=1.787 Kg m2 s-2
rotational kinetic energy final = K rot,f = 1/2 I w2
= 0.8935 Kg m2 s-2
total kinetic energy= Kf + Krot, f = 2.6805 Kg m2 s-2
total energy = kinetic energy + potential energy
E ( total , initial) = mgh ( initial kinetic energy =0)
E(total ,initial) = 1.793 Kg m2 s-2
E( total, final) = total kinetic energy =2.6805 Kg m2 s-2
Trial 1
Similarly above values can be calculated for silver ball
moment of inertia of silver ball= 2/5 mr2
Cylinder Time Started (s) Time stopped(s) Time taken between the two gates(s)Trial 1
1.23 1.83 0.60 Trial 2 1.23 1.81 0.58 Trial 3 1.28 1.81 0.53 Average 0.57Related Questions
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