The apparatus shown in the figure below uses a spring to launch a small block al

Question

The apparatus shown in the figure below uses a spring to launch a small block along a track. A latch holds the block of mass M in place against the compressed spring (spring constant k) as shown. When the ring is raised the block is launched along the track. The parts of the track from A to B and from C to D can be considered frictionless for this problem. The part from B to C has significant friction (coefficient of sliding friction, ).

When the block is launched, it gets through the frictional part, rises up the ramp to the point D, a height h above the straight part of the ramp. It then slides back down. On its return, it gets to the point B and stops. For the items below choose the symbol that best completes the sentence: greater than (>); less than (<); equals (=), positive (+), negative (), zero (0). If none complete the sentence correctly, choose N. Explain your answers

(a) The potential energy stored in the spring just before the mass is released is  ________ the kinetic energy of the mass as it is reaches the point B for the first time.

(b) The potential energy stored in the spring just before the mass is released is _________ the gravitational potential energy of the mass as it is reaches the point D. (Take the zero of gravitational PE at the level of the straight part of the track.)

(c) In the overall motion, the magnitude of the total work done by the frictional force is ________ the magnitude of the total work done by the spring force.

(d) The total work done by the gravitational force throughout the whole motion is _________.

(e) The total work done by the friction force throughout the whole motion is__________.

Explanation / Answer

(a) Equal ,
since there is no loss in the energy from A to B , hence the total potential energy of the spring will be equal to the kinetic energy.
(b)Greater ,
because the energy that converted into the gravitational energy is somwhat less becasue some energy is lost in the friction from B to C
(c) Equal
Since all the energy is lost in the friction only
(d) Mgh
(e) Work done by friction force = friction force*distance
Friction force= u*Normal reaction (where u is coefficient of friction )
Friction force = u*Mg
Since the distnace is covered twice therefore
the total distance will be = 2L
Hence the work done = uMg*2L

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.