Physics 125 Test 3 April 23, 2020 Name Part 1 Below Are 6 Sh

Physics 125 Test 3 Apr 23 2020 Name Part 1 Below Are 6 Shor

Below are 6 short workout questions. Answer any 5 of the 6 questions. You must show all your work to receive any credit. You may do the remaining question as a bonus. (You may use your book, notes, and old homework, but not other people.)

Paper For Above instruction

Question 1a) A mass travels around a loop. The surfaces are frictionless. Student A states that since the normal force is non-conservative, the energy of the mass at the bottom of the loop is not equal to the energy of the mass at the top of the loop. Student B states that the work done by the normal force would just be the normal force times the distance traveled by the mass going from the bottom of the loop to the top of the loop. Student C states that the energy at the bottom of the loop is equal to the energy at the top of the loop. Which student is correct? Explain your reasoning.

Question 1b) A bullet of mass m and velocity ð‘£" is fired into a block M initially at rest. The bullet remains in the block. Student A claims that the kinetic energy of the bullet-block system after the bullet strikes the block is equal to the kinetic energy of the bullet before the bullet strikes the block. Student B disagrees. Which student is correct? Explain your reasoning.

Question 1c) A conservative force moves an object along three possible paths (A, B, and C). The object is moved from its initial position, i, to its final position, f. Student 1 claims that the ranking of the work done by this force along each of these paths is ð‘Š$ > ð‘Š% > ð‘Š&. Student 2 claims that the work along the various paths are ranked ð‘Š$

Question 1d) A 2 kg mass of putty traveling at 5 m/s collides and sticks to a 3 kg mass of putty traveling at 4 m/s as shown below. Student A claims that the V is given by 2(5) + 3(4) = (2+3)V. Student B states you need to use ð¸(= ð¸). Student C states neither A nor B are correct. Which student is correct? Explain your reasoning.

Question 4a) A 3 kg mass initially at rest is moving in 1-d. The potential energy of the 3 kg happens to be given by U = 8 - 4 ð‘¥ + 2 ð‘¥8. If the 3 kg mass is initially at x = 2 m, what is the energy of the 3 kg mass?

Question 4b) What is the object’s velocity at x = 1m?

Question 4c) At what values of x, will the 3 kg mass experience no force?

Question 4d) A 10 kg mass initially traveling to the right at 15 m/s breaks up into 6 kg and 4 kg masses. The 4 kg mass has a velocity of 10 m/s and makes a 30° with the x-axis. What are the x and y components of velocity of the 6 kg mass?

Part 2: Below are 3 longer workout questions.

Question 1) Mass m, initially at rest, is compressing a spring of spring constant k by a distance x. The spring is released, and the mass travels around the circular loop of radius R.

a) Find an expression for the velocity of the mass at the top of the loop. ð‘£CDE =

b) Find an expression for the normal force that the track exerts on the mass at the top of the loop. N =

c) After the mass travels around the loop, it starts traveling up an inclined plane. Find an expression for the maximum height, H, that the block reaches as it travels up the inclined plane? H =

Question 2) Mass M, initially at rest, hangs from a string of length R. It is struck by a mass m traveling to the right with a velocity ð‘£". After the collision, the velocity of mass m is ð‘£"/3.

a) What is the velocity of M immediately after the collision? V =

b) What is the velocity of mass M when it reaches the top of the circle? ð‘£CDE =

c) Find an expression for the tension in the string at the top of the circle. T =

d) Find an expression for ð‘£" if M JUST makes it around the circle. ð‘£"=

References

• Serway, R. A., & Jewett, J. W. (2018). Physics for Scientists and Engineers with Modern Physics (10th ed.). Cengage Learning.
• Halliday, D., Resnick, R., & Walker, J. (2014). Fundamentals of Physics (10th ed.). Wiley.
• Tipler, P. A., & Mosca, G. (2007). Physics for Scientists and Engineers (6th ed.). W. H. Freeman.
• Giancoli, D. C. (2014). Physics for Scientists and Engineers with Modern Physics (4th ed.). Pearson.
• Newton, I. (1687). Philosophiæ Naturalis Principia Mathematica.
• Feynman, R. P., Leighton, R. B., & Sands, M. (2011). The Feynman Lectures on Physics.
• Young, H. D., & Freedman, R. A. (2019). University Physics with Modern Physics (15th ed.). Pearson.
• Kibble, T. W. B., & Berkshire, F. H. (2004). Classical Mechanics. Imperial College Press.
• Crandall, S. H., Dahl, M. M., & Verhey, R. P. (2006). Mechanical Engineering Design. McGraw-Hill.
• Beer, F. P., & Johnston, E. R. (2013). Vector Mechanics for Engineers: Dynamics. McGraw-Hill.