Question

scenario:
your class designed a small roller coaster for marbles. the marble starts at the top of a ramp, rolls through a loop, and stops at the end.
prompt:
explain what happens to the marble’s energy as it moves through the roller coaster.

• claim: describe how the marble’s potential, kinetic, and thermal energy change.
• evidence: use specific examples from the marble’s motion.
• reasoning: explain why these changes happen using energy transfer principles.

Explanation:

• Claim: The marble's potential energy decreases as it moves down the ramp (due to lower height), kinetic energy increases (as it speeds up), and thermal energy increases (from friction). At the top of the loop, potential energy is higher than at the bottom of the loop (higher height), kinetic energy is lower (slower speed compared to bottom of loop), and thermal energy continues to increase. At the end, potential energy is low (height near - ground level), kinetic energy is zero (stopped), and thermal energy is at its maximum (from all the friction during the motion).
• Evidence: When starting at the top of the ramp (high height), it has high potential energy. As it rolls down (height decreases), it speeds up (kinetic energy increase). The loop - when going up the loop, speed decreases (kinetic energy decrease) and height increases (potential energy increase). Friction is evident as the marble stops at the end (energy lost as heat - thermal energy).
• Reasoning: According to the law of conservation of energy, energy is transferred. Gravitational force does work on the marble as it moves down the ramp (potential to kinetic). Friction (a non - conservative force) acts on the marble throughout its motion, converting mechanical energy (potential + kinetic) into thermal energy. In the loop, there is a trade - off between potential and kinetic energy (similar to a pendulum - like motion in terms of energy transfer between these two forms), but thermal energy is always increasing due to friction.

Answer:

• Claim: Potential energy decreases (from top of ramp to end), kinetic energy first increases (down ramp), then varies (in loop - decreases going up, increases going down loop), and finally becomes zero (at end). Thermal energy continuously increases.
• Evidence: At top of ramp (high potential, low kinetic), speeding up down ramp (kinetic increase, potential decrease), slower at top of loop (kinetic decrease, potential increase), stopped at end (kinetic zero). Friction causes heating (thermal energy).
• Reasoning: Energy transfer (potential to kinetic via gravity, kinetic to potential in loop, and mechanical to thermal via friction) follows conservation of energy principles (total energy = mechanical + thermal, with mechanical being potential + kinetic).