A small cart of mass 0.40 kg is released from rest at the top of a gentle incline of…
PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
A small cart of mass 0.40 kg is released from rest at the top of a gentle incline of vertical height 0.60 m. A qualitative energy bar chart prepared by a student is described as follows:
• Point A (at release): one bar labeled “gravitational potential energy,” drawn 6 grid squares tall; all other energy bars drawn with zero height.
• Point B (midway down the incline): two bars are drawn— the gravitational potential energy bar is 3 grid squares tall and the kinetic energy bar is 3 grid squares tall.
• Point C (bottom of the incline): one bar labeled “kinetic energy,” drawn 6 grid squares tall; the gravitational potential energy bar is drawn with zero height.
Assume the cart–incline system is isolated and friction is negligible.
(a) Describe how the student’s bar chart represents the relationship between kinetic energy and gravitational potential energy for the cart as it moves from Point A to Point C.
(b) Explain whether the bar chart is consistent with the principle of conservation of energy.
(c) Suppose a rough spot on the incline at Point B converts some mechanical energy to thermal energy. Describe qualitatively how the bars at Point B should be modified to reflect this change while still conserving total energy.