Question

Learning Goal: To practice Problem-SolvingStrategy 7.2 Conservation of energy with conservative forces.

A basket of negligible weight hangs from a vertical spring scale offorce constant1500 . If you suddenly put an adobebrick of mass3.00 in the basket, find the maximum distance thatthespring will stretch.

Problem-Solving Strategy 7.2 Conservation of energy with conservativeforces

1. Identify the system youwill analyze, and decide on the initial and final states (positionsand velocities) you will use in solving the problem. Draw oneormore sketches showing the initial and finalstates.
2. Define your coordinatesystem, particularly the zero points for gravitational and elasticpotential energies (the point at which $y=0$ in the case of gravitational potentialenergy or at which thespring is relaxed in the case of elasticpotential energy).
3. List the initial andfinal kinetic and potential energies?that is, $K_i$ , , $U_i$ , and $U_f$ . Some of these will be known and someunknown. Usealgebraic symbols for any unknown coordinates orvelocities. Keep in mind that potential energy includes both gravitational and elasticpotential energy.

4. Writeexpressions for the total initial mechanical energy and for thetotal final mechanical energy, equate them, and solve to findwhateverunknown quantity is required.

5. Take a hardlook at your results to see whether they make sense. Are theywithin the general range of magnitudes you expected? If you changeoneof the given quantities, do the results change in a way you canpredict?

SET UPBefore writing any equations, organizeyour information and draw appropriate diagrams.Part AWhich of the following statements about theproblem are true?Check all that apply.

The spring is initially unstretched. After the brick has been placed in the basket,the spring is stretched. When the brick is first placed into the basket,it has zero velocity. When the brick has stretched the spring to itsfull extent, it has zero velocity. The brick’s final position is lower thanits initial position.

MY ANSWERS ARE WRONG?!?! PLEASE HELP!

Answer 1

Answer 2

They are all true statements.