A system comprising two blocks is shown, one of which is on an inclined plane. T

Question

A system comprising two blocks is shown, one of which is on an inclined plane. The pulley is of negligible mass and is frictionless. The system starts from rest at position 1 and accelerates. Measurements taken when the blocks reach position 2 indicate that

(1) the kinetic energy of block A has changed by 330 J,(2) the potential energy of block A has changed by 588 J,(3) the kinetic energy of block B has changed by 110 J,(4) the potential energy of block B has changed by 98 J.

The amount of mechanical energy that has been converted to heat because of friction is

A) 12 J

B) 50 J

C) 258 J

D) 478 J

E) 710 J

Explanation / Answer

Initial total energy of the system = Initial K.E. of A + Initial P.E. of A + Initial K.E. of B + Initial P.E. of B Final total energy of the system = Final K.E. of A + Final P.E. of A + Final K.E. of B + Final P.E. of B amount of mechanical energy that has been converted to heat because of friction = Q = Final total energy of the system-Initial total energy of the system =>Q = Final K.E. of A + Final P.E. of A + Final K.E. of B + Final P.E. of B - Initial K.E. of A - Initial P.E. of A - Initial K.E. of B - Initial P.E. of B =>Q = Change in K.E. of A + Change in P.E. of A + Change in K.E. of B + Change in P.E. of B K.E. of A and B will increase as the blocks accelerates P.E. of B will increase as it is moving upwards P.E. of A will decrease as it is moving downwards =>Q = 330-588+110+98 = -50 J So magnitude = 50 J.........Option B

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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