A piano is brought upstairs by two workers. Due to a mistake by one of the worke

Question

A piano is brought upstairs by two workers. Due to a mistake by one of the workers, the piano rolls down the stairs and finally comes to rest by the outside door. Which sequence best describes the energy transformations for the piano from the moment it is being brought upstairs to when it stops by the door? A. Potential energy -> Kinetic energy -> thermal energy of the ground and piano B. Ground energy -> Potential Energy -> Thermal energy -> kinetic energy of the piano C. PE -> KE -> PE -> TE of the piano and ground D. KE -> PE -> KE

Explanation / Answer

1c you can actually eliminate this one sequentially. work is definitely done since a volume that should be expanding due to the gas formed, is actually being forced back. so d) is wrong. also, a) and b) are essentially 2 sides to the same coin. in order for positive work to be done on the surrounding, the work has to come from somewhere, thus negative work must be done by the system. Since they can't be both right, they're both wrong. But the point is, the outside force must be putting in extra energy onto the system in order to compress the volume of the gas, when it should be expanding due to the reaction. 2a when the piano is raised to a higher level, it gains gravitational potential energy. but when it falls back down and gains speed, that potential energy is turned into kinetic energy, similar to dropping a ball from a height. What slows the piano down is friction, rubbing of the piano and the ground, which will in turn produce heat. the kinetic energy is thus transferred into heat.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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