Ekins P7A Lab 3
.pdf
keyboard_arrow_up
School
University of California, Berkeley *
*We aren’t endorsed by this school
Course
7A
Subject
Physics
Date
Apr 3, 2024
Type
Pages
9
Uploaded by Lkat57
Physics 7A Dynamics Lab, v.5.0 p-1 Lab 3: Dynamics Introduction This lab has two purposes. First, starting in the prelab, you'll address increasingly difficult versions of a standard exam-level force problem about a cart and pulley. Then in lab you'll test your answers experimentally. In addition, you'll do experiments and answer questions designed to highlight some of the subtle conceptual aspects of Newton’s laws, and how these relate to common-sense force intuitions. Prelab Questions: An exam-level force problem [Complete these questions before coming to lab! Your GSI will discuss them at the beginning of the lab.] Consider the lab set-up below. A cart of mass m_,,, is connected to a vertically hanging mass, of mass my,,.. The cart moves with negligible friction. Inlab, you will give the cart a brief push away from the pulley, and then let it go. —— 1 —_— adjustable end stop Figure 7.1 Equipment Setup A. Draw separate free-body diagrams (FBDs) for the cart and for the hanging mass. Your diagrams should describe those objects after you finish pushing the cart, but while it's still traveling away from the pulley. Label each force acting on each object. T F(n) F(9) Flg) B. After you finish pushing the cart, what force (if any) is making the cart slide away from the pulley? Explain. After the initial push, the acceleration caused by the applied force makes the cart continue to slide away from the pulley. There is no applied force currently present though. Even though the applied force is no longer acting upon the object, the object will remain moving in the direction of the acceleration until the point at which the tension of the pulley overcomes the initially applied force.
Physics 7A Dynamics Lab, v.5.0 p.2 C. Interms of m,, My, and g, find the cart’s acceleration. Show your work here. (During the lab, you will plug in the relevant numbers, to make a numerical prediction.) Horizontal Mass: F =m2a =T - m2g Cart: F =m1a =T (left is positive in the horizontal direction) m2a = (m1a) - m2g a(m2-mil) =-m2g a=-m2g/(m2-m1) D. Consider the time after the cart reverses direction and starts moving back towards the pulley. (i) Inwhat ways, if any, must we modify the free-body diagrams from question A? Explain, and draw the correct FBDs here. The free-body diagrams will be changed to have a tension that is smaller than the force of gravity for the hanging mass FBD. The cart's FBD will need to have no applied force, making the tension the sole horizontal force. T T F(n) Fo F@ (ii) Is the new acceleration bigger than, smaller than, or the same as the cart’s acceleration when it was traveling away from the pulley? Relate your answer to (i). The new acceleration is in the opposite direction, so the new acceleration will be less than the original. In (Di), the tension of the cart FBD is equal to the net force as the acceleration will only be in the negative horizontal direction at this interval of time. End of pre-lab questions. The lab starts on the next page GSI's Initials:
Physics 7A Dynamics Lab, v.5.0 p.3 Cart & hanging mass 1. In this first experiment, you'll test your prelab prediction about the acceleration. ¢ Remove the brake from the cart, if it's attached. ¢ Usea scale to measure m,,,, and .. Don't forget to include the mass of the “hook” in . With these values, predict the cart’s acceleration, using your answer to prelab question C. My =_5509 Mygng =59 Predicted acceleration = _0-089 m/s"2 4 If the track is currently set up as a ramp, lay it flat on the lab bench, and make sure it’s level. 4 Using the computer software "7A_MotionDetector.mbl" from our earlier labs, set up the screen to show an acceleration graph—and no other graphs. 4 Set up the motion detector, and run the experiment. To determine the value of the acceleration as accurately as possible, adjust the acceleration axis. A Measured acceleration = 01 mis"2 2. By what percentage does the measured acceleration differ from the predicted acceleration? Show your work. Measured value - expected value / expected value x 100% (0.1-0.089) /0.089 = 0.1235 = 12.35% 3. List some reasons why your predicted and measured acceleration disagree. How could the experiment be improved? The predicted acceleration differs from the measured acceleration because there are other forces that we considered negligible in our calculations. For example, the track had friction and the string moving over the pulley had friction so these forces were unaccounted for in our expected value. Additionally, the string has a mass that was not taken into consideration. The experiment could be improved by utilizing materials with smaller amounts of friction and mass (in regards to the string).
Physics 7A Dynamics Lab, v.5.0 p-4 4.* After you let the cart go, as it moves back and forth across the track, is the tension in the string more than my,, g, equal to my,. g, less than m,, ¢? Explain, both mathematically and conceptually. As the cart moves back and forth, the tension of the string changes and oscillates among being less than, equal to, and greater than m(hang) g. As the cart moves away from the pulley, the hanging mass moves upwards. The only forces acting on the hanging mass are tension in the upwards direction and the force of gravity, which is constant. In order for the hanging mass to move upwards as the cart moves away from the pulley, the tension must be greater than m2g. When the cart moves towards the pulley, the hanging mass moves in the downward direction, so the tension must be less than the force of gravity. There is a point in time when the tension value is changing that it will equal m2g because it cannot achieve a value of + - m2g without being equal to m2g at a point. Horizontal Mass: F =m2a =T - m2g Cart: F =m1a =T (left is positive in the horizontal direction) T =m2g + m2a when cart is moving in the positive horizontal direction T>m2g T =m2g - m2a when cart is moving in the negative horizontal direction T<m2g 5. (Prediction) What will the position, velocity, and acceleration graphs of the cart look like if you repeat the above experiment, but with the following twist: after the cart has reversed direction and traveled about half way back towards the pulley, you'll catch the hanging mass, allowing the string to go slack. In other words, you'll “turn off” the tension force. As usual, draw your predictions before doing the experiment. Let “towards the pulley” be the positive direction, and neglect friction. The actual graphs were very close to the predictions N T art hanging @t hanging ant hanging direction caught direction caught direction caught ¢ Before running the experiment, pull down the View menu, select Graph Layout and choose “Three panes”. Make sure one of the graphs shows position, another shows velocity, and a third shows acceleration. As usual, you can change graphs by double clicking them. Make sure they all have the same time scale. Set the time scale onall three graphs equal to 4 sec. (You can change this setting if needed; but all three graphs must have the same time scale.) ¢ Make sure the motion detector is at the other end of the track from the pulley. ¢ Run the experiment. Change the scale of the graphs, if needed, to see the results more clearly. # If the actual graphs disagree with your predictions, sketch them on the above axes, using a different color or a dashed line. Omit the beginning segment of the graph when your hand was still pushing the cart.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Related Questions
Write complete solution
arrow_forward
QUIZ IN COMPONENT METHOD
A - F = 250 N, 57° E of S
B - F2 = 175 N, 80° S of W
%3D
C - F3 = 430 N, 72° W of N
D - F4 = 118 N, 61° S of E
E - F5 = 313 N, 38° N of W
%3D
COMPUTE SUM OF THE FOLLOWING:
1. A & C
2. B &D
3. А, В &E
4. C, D & E
5. А, В, С, D &E
arrow_forward
review Engineering Dynamics
Part B
What is the normal reaction on the car when the it is at B?
Express your answer to three significant figures and include the appropriate units.
NB =
Part C
What is the normal reaction on the car when the it is at C
C?
Express your answer to three significant figures and include the appropriate units.
NC =
arrow_forward
A. Perfectly inelastic collisions
Figure 1 shows the schematic of the set up for this part of experiment. Before the collision,
cart 2 should be at rest.
motion detector
added mass
cart 1
velcro
track
cart 2
mass of cart 1: 1009.6 g
g
mass of cart 2: 510
measured velocity of cart 1 before collision:
0.642 m/s
measured velocity of the carts after the collision: 0.379 m/s
expected velocity of the carts after the collision, based on conservation of momentum:
(show calculation here)
percent difference between measured and expected final velocities:
measured total kinetic energy before the collision:
measured total kinetic energy after the collision:
0.4265
11.14/0
m
see
arrow_forward
B. Exercises for Skill Subjects/Analysis Questions Using HOTS for Content Subjects
Exercise 1: Calculate me!
A 100-gram ball m1, and a 200-gram ball m2, connected by a rod with a length of 60 cm.
the mass of the rod is ignored. The axis or rotation is located at the center of the rod. What
is the momentum of inertia of the balls about the axis rotation?
Illustration:
A
Ace
m1
m2
B
arrow_forward
Equation Jeopardy 1 The equations below describe one or more physical
processes. Solve the equations for the unknowns and write a problem state-
ment for which the equations are a satisfactory solution.
*
-(0.001 kg) (9.8 N/kg) + T sin 88° = 0
(−5.0 × 10-³ C)Ex + T cos 88° = 0
arrow_forward
This is NOT graded
This picture has 3 questions. Please solve and explain question number 1
arrow_forward
Science 24: Module 4
Assignment Booklet 4B
For questions 17 to 21, read each question carefully. Decide which of the choices
BEST answers the question. Place your answer in the blank space given.
17. Two vehicles with the same mass and travelling the same speed in
opposite directions hit head on, What is the total momentum immediately
after the collision?
A. zero
B. double that of each car
C. one half that of each car
D. four times that of each car
Use the following diagram to answer questions 18 and 19.
Car A
Car B
18. If Car A has a greater momentum than Car B, what will happen to both
vehicles immediately after they collide?
A. They will travel to the right.
B. They will travel to the left.
C. They will stop immediately.
D. It cannot be determined from this information.
19. If both cars are travelling the same speed and Car B has a greater mass,
what will happen to both vehicles after they collide?
A. They will travel to the right.
B. They will travel to the left.
C. They will stop…
arrow_forward
University Physics 1 - Conservation of Momentum
I need help with this problem and an explanation of the solutions described below:
Pick one of the collisions (identify which one it is) from the air track collision experiment.
Collision 2 ( described in the image below)
and calculate the mechanical energy both before and after the collision. Was energy lost or gained? If it was lost, where did it go? If it was gained, where did it come from?
arrow_forward
F1
RDY
RAY
The figure above is a pin-joint frame with horizontal member length l = 3m and vertical member length h = 5m. (Note that the diagram is not to scale.)
You are given that F = 48KN, RAY = 16KN and Rpy = 32kN.
Use the method of sections to calculate the forces in members BC, FC and FE.
Enter your answers in kilonewtons (kN) correct to 2 decimal places.
Enter FBC :
kN
ype here to search
arrow_forward
2. LO:3 Explain your answer.
Explanation:
Ⓡ
v=0
Explain:
Ē = 0
net
= 50 km/hr
v=
F
net
= ?
B
to
8. LO: 3-A block is pushed upon by a constant force (assume that no other forces act on the block). The force
suddenly stops acting. The block will
A. Stop moving as soon as the force is zero.
B. Continue to move with the velocity at the instant the force stops acting.
C. keeps moving with its speed decreasing, stopping eventually.
9. LO:4 - A 63.0-kg sprinter starts a race with an acceleration of 4.20 m/s². What is the net external force
on him?
arrow_forward
Question 4 Determine the reaction at the supports for the following system
E
|-3-1-3-1 -3 -1 -3-1
arrow_forward
a.) If an object is already moving and you applied another force parallel to it and with the same direction, does this mean that another counter force will be generated? Explain.
b.) Considering question (a), what if you applied a force lower than the force of momentum (and gravity, etc.) on the object, will it generate a counter force? Explain.
c.) On our activity, pushing the object at rest generates a counter force. How is this?
arrow_forward
1
arrow_forward
Q24. As shown in the image below, the 16-kg block A and the 42-kg block B connected by the weightless, frictionless pulley
system are released from rest. Determine the speed of block B when block A has displaced downwards by 0.7 m. Please pay
attention: the numbers may change since they are randomized. Your answer must include 3 places after the decimal point, and
proper Sl unit.
A
Answer:
d
O
[o k
B
arrow_forward
TU0%
3. Describe the motion of the freezer. Will its velocity change? If yes, how?
4. Which object has more inertia - a bowling ball or a tennis ball? Explain.
5. How does inertia influence your ability to roll a bowling ball versus a tennis ball? Explain.
6. Write Newton's First Law of Motion in your own words. You MAY NOT use the following
words: at rest, motion, constant velocity, net force.
7. Use Newton's First Law of Motion and the concept of inertia to explain what happens to a
in a head-on car accident who is not wearing a seat belt. How does wearing a seat
person
belt help?
pe here to search
arrow_forward
draw schema
arrow_forward
I Review I
Three objects A, B, and C are moving as shown in the
figure below (Figure 1). Assume that vA =
VB = 9.0 m/s, and vc = 3.2 m/s.
12.0 m/s,
Part C
Find the x-component of the net momentum of the particles if we define the system to consist of B and C.
Express your answer in kilogram meters per second.
ΑΣφ
?
Px =
kg · m/s
Submit
Request Answer
Part D
Figure
1 of 1
Find the y-component of the net momentum of the particles if we define the system to consist of B and C.
Express your answer in kilogram meters per second.
B60°
?
5.0 kg
6.0 kg
10.0 kg
Py =
kg · m/s
Submit
Request Answer
Gutɔtivn15 a5ktu iIL TIEW Sunjttt5 uu TIOt Coulnt agalist youi qut5tIOIT COUTIC.
arrow_forward
Review I Constants
Three objects A, B, and C are moving as shown in the
figure below (Figure 1). Assume that vA = 12.0 m/s,
VB = 9.0 m/s, and vc = 3.2 m/s.
Part E
%3D
Find the x-component of the net momentum of the particles if we define the system to consist of all three objects.
Express your answer in kilogram meters per second.
?
Px =
kg · m/s
Submit
Request Answer
Part F
Figure
1 of 1
Find the y-component of the net momentum of the particles if we define the system to consist of all three objects.
Express your answer in kilogram meters per second.
A
?
5.0 kg
B 60°
6.0 kg
10.0 kg
Ру
kg m/s
%3D
Submit
Request Answer
arrow_forward
Q2) State whether the following statements are true (T) or false (F). Correct the false statements
(answer ten points only)
1. The dynamic means the study of the motion of particles and bodies without taking into account the
factors that cause this motion.
2. Calculations in dynamics involve mass and force.
3. The velocity is a scalar quantity.
4. The displacement is a vector quantity.
5. The speedometer in a car measures the speed, which is a vector quantity.
6. A position-time graph is a useful tool for analyzing the friction of bodies.
7. The instantaneous velocity can be calculated graphically from the time-position graph by finding
the slope of the line between two points on this graph.
8. The average and instantaneous acceleration can be estimated graphically from the time-position
graph.
9. The free-body diagram shows all the internal forces that exerted on an object.
10. Friction acts to resist the motion of the object when two objects are in not contact.
11. The static…
arrow_forward
Please solve this question in handwriting step by step.
arrow_forward
Please answer question and just send me the paper solutions asap dont type the answer please question 1 please give me the right solutions and answers please and label the given and draw a diagram and show the work please help me faster asap
arrow_forward
HW 5.1
(must submit work on a separate sheet of paper title HW 5.1 AND complete Google Form)
1. The earth exerts a force of 2900 N on an orbiting communications satellite that is 40 mi
above the Earth. What is the magnitude of the force the satellite will exert on the
earth?
2. A stone is dropped from the top of a high cliff with zero initial velocity. In which
system is the net momentum zero as the stone falls freely?
a. the stone and the Earth
b. the stone itself
C. None of these
d. the stone and the person who drops it
3. When an apple falls from a tree and strikes the ground without bouncing, what
happens to its momentum?
a) The momentum of the apple after striking the ground is reversed.
b) The speed of the apple is equal and opposite to the speed of the Earth.
C) The momentum of the apple while falling is increasingly smaller.
d) The momentum of the falling apple is transferred to the Earth.
4. Two 0.5 kg balls move away from each other, one traveling 3 m/s to the right, the…
arrow_forward
1.
Mechanical structure of 3-DOF RPY wrist is shown in Figure 1
Joint 1
Joint 2
Joint 3
Tool point
P
Arm end
Roil
Pitch
Yaw
Figure 1 3-DOF RPY wrist configuration
Formulate the forward kinematic model and describe the steps for frame assignment to the links of the
given manipulator.
b. Determine the D-H parameters of the tool point P with respect to the base for the 3 DOF manipulator
а.
Compute the orientation and position of the too point P for the displacement variable el=60°, e2=120° and
ө3-30°.
с.
arrow_forward
How do I set up?
arrow_forward
4
arrow_forward
Suggest some likely sources of error that could be responsible for the difference between your measured and predicted values for the horizontal distance traveled by the projectile at the different angles used in this experiment. “Human error” is not acceptable without saying specifically what error the human could have made. “Calculation error” is also not acceptable—if you are worried about whether the calculation is correct, consult with your classmates and/or someone you trust to do the calculation correctly.
PROCEDURE
Part I
Place a marble launcher on the table, oriented so it points straight upward (θ = 90°). Pull the launch mechanism back to the first (nearest) launch position and place a marble into the launcher. Practice quickly releasing the launch mechanism and get a sense for the maximum height the marble will reach after it is launched.
Hold a meter stick beside the marble launcher so that the zero end is beside the marble. Launch the marble and record the maximum…
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning
Related Questions
- Write complete solutionarrow_forwardQUIZ IN COMPONENT METHOD A - F = 250 N, 57° E of S B - F2 = 175 N, 80° S of W %3D C - F3 = 430 N, 72° W of N D - F4 = 118 N, 61° S of E E - F5 = 313 N, 38° N of W %3D COMPUTE SUM OF THE FOLLOWING: 1. A & C 2. B &D 3. А, В &E 4. C, D & E 5. А, В, С, D &Earrow_forwardreview Engineering Dynamics Part B What is the normal reaction on the car when the it is at B? Express your answer to three significant figures and include the appropriate units. NB = Part C What is the normal reaction on the car when the it is at C C? Express your answer to three significant figures and include the appropriate units. NC =arrow_forward
- A. Perfectly inelastic collisions Figure 1 shows the schematic of the set up for this part of experiment. Before the collision, cart 2 should be at rest. motion detector added mass cart 1 velcro track cart 2 mass of cart 1: 1009.6 g g mass of cart 2: 510 measured velocity of cart 1 before collision: 0.642 m/s measured velocity of the carts after the collision: 0.379 m/s expected velocity of the carts after the collision, based on conservation of momentum: (show calculation here) percent difference between measured and expected final velocities: measured total kinetic energy before the collision: measured total kinetic energy after the collision: 0.4265 11.14/0 m seearrow_forwardB. Exercises for Skill Subjects/Analysis Questions Using HOTS for Content Subjects Exercise 1: Calculate me! A 100-gram ball m1, and a 200-gram ball m2, connected by a rod with a length of 60 cm. the mass of the rod is ignored. The axis or rotation is located at the center of the rod. What is the momentum of inertia of the balls about the axis rotation? Illustration: A Ace m1 m2 Barrow_forwardEquation Jeopardy 1 The equations below describe one or more physical processes. Solve the equations for the unknowns and write a problem state- ment for which the equations are a satisfactory solution. * -(0.001 kg) (9.8 N/kg) + T sin 88° = 0 (−5.0 × 10-³ C)Ex + T cos 88° = 0arrow_forward
- This is NOT graded This picture has 3 questions. Please solve and explain question number 1arrow_forwardScience 24: Module 4 Assignment Booklet 4B For questions 17 to 21, read each question carefully. Decide which of the choices BEST answers the question. Place your answer in the blank space given. 17. Two vehicles with the same mass and travelling the same speed in opposite directions hit head on, What is the total momentum immediately after the collision? A. zero B. double that of each car C. one half that of each car D. four times that of each car Use the following diagram to answer questions 18 and 19. Car A Car B 18. If Car A has a greater momentum than Car B, what will happen to both vehicles immediately after they collide? A. They will travel to the right. B. They will travel to the left. C. They will stop immediately. D. It cannot be determined from this information. 19. If both cars are travelling the same speed and Car B has a greater mass, what will happen to both vehicles after they collide? A. They will travel to the right. B. They will travel to the left. C. They will stop…arrow_forwardUniversity Physics 1 - Conservation of Momentum I need help with this problem and an explanation of the solutions described below: Pick one of the collisions (identify which one it is) from the air track collision experiment. Collision 2 ( described in the image below) and calculate the mechanical energy both before and after the collision. Was energy lost or gained? If it was lost, where did it go? If it was gained, where did it come from?arrow_forward
- F1 RDY RAY The figure above is a pin-joint frame with horizontal member length l = 3m and vertical member length h = 5m. (Note that the diagram is not to scale.) You are given that F = 48KN, RAY = 16KN and Rpy = 32kN. Use the method of sections to calculate the forces in members BC, FC and FE. Enter your answers in kilonewtons (kN) correct to 2 decimal places. Enter FBC : kN ype here to searcharrow_forward2. LO:3 Explain your answer. Explanation: Ⓡ v=0 Explain: Ē = 0 net = 50 km/hr v= F net = ? B to 8. LO: 3-A block is pushed upon by a constant force (assume that no other forces act on the block). The force suddenly stops acting. The block will A. Stop moving as soon as the force is zero. B. Continue to move with the velocity at the instant the force stops acting. C. keeps moving with its speed decreasing, stopping eventually. 9. LO:4 - A 63.0-kg sprinter starts a race with an acceleration of 4.20 m/s². What is the net external force on him?arrow_forwardQuestion 4 Determine the reaction at the supports for the following system E |-3-1-3-1 -3 -1 -3-1arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning