Physics B3

Question 1

First law of thermodynamics

Answer 1

the total energy in a system and its surroundings remains constant

Question 2

Perpetual motion machine

Answer 2

“the perfect machine”, a hypothetical machine where all the input energy converts completely into mechanical energy

Question 3

second law of thermodynamics

Answer 3

-thermal energy flows from hot to cold naturally but not cold to hot
-work is needed to make thermal energy go from cold to hot

Question 4

heat engine

Answer 4

a device that turns heat into mechanical energy

Question 5

heat pump

Answer 5

advice that converts mechanical energy into heat

Question 6

When you rub two sticks together and they ignite, is the work done on the sticks positive or
negative?

Answer 6

Positive work is when heat is added to the system, increasing the temperature of the system.
When rubbing two sticks together, you are adding heat and increasing the internal energy of
the system (sticks)

Question 7

If you leave the fridge door open, will you cool the room down on a hot day?

Answer 7

NOOO – you will just cause the compressor to work harder!

Question 8

open system

Answer 8

system that exchanges both matter and energy with its surroundings

Question 9

closed system

Answer 9

system that exchanges energy with its surroundings

Question 10

isolated system

Answer 10

system that can’t exchange either matter or energy with its surroundings

Question 11

gunpowder engine: technology

Answer 11

experimented with gases generated by an explosion inside the engine which drove a piston into the cylinder

Question 12

gunpowder engine: drawbacks

Answer 12

engine wasn’t developed because of explosion hazards and there was no internal mechanism to pull the pistol back so it could be used more than once

Question 13

heat engine: technology

Answer 13

-first heat engine in 1690
-used heat to create steam to do work

Question 14

heat engine: drawbacks

Answer 14

didn’t pursue because he couldn’t make the drum for water to be heated