Question

Write the first law of thermodynamics in equation form. For each process or system,state whether each term is +, - , 0.

a. A man stretches a spring. System: spring.

b. A pinewood block slides to a stop on a pinewood table. System: block and table.

c. A pinewood block slides to a stop on a pinewood table. System: table

d. A gas is compressed adiabatically. System: gas

e. A gas in a container is compressed at constant pressure. System: gas

Answer 1

The first law of thermo dynamics can be expressed as

Question
a	+ work done by the man to stretch the spring	+ internal energy increases and is stored as tension	+ heat dissipated by the spring while it is stretched. If no change in temeprature it is 0
b	0 No work is done on the system as the block is already in motion at the start of analysis	- Internal energy is lost as the kinetic energy of the blockhas come to 0	+ Work done by the system to bring the block to rest throgh friction
c	+ Work done by the block on the table through frictional heat	0	+ Work done by the table to bring the block to rest
d	+ Work done in compressing the gas	+ Internal energy increases as the molecules collide more due to less volume	0 No work is done by the system as there is no change in temperature and no motion in sytem components