HEAT ENERGY
What is the unit for heat?
joule
What is the unit of force?
joules
In the human body, what does the elbow joint act as?
fulcrum, gear, or lever?
fulcrum
What is the unit for power?
watts
Give an example of heat transfer by convection.
examples could be...
Cool breeze that blows from the water toward the beach during the day
Air moving from the Earth's equator toward the north pole
Transfer of heat to cooler parts of the room from a radiator
Water molecules being heated on the stove
WHICH IS CORRECT
Heat will always flow from a body of higher temperature to a body of lower temperature.
OR
Heat will always flow from a body of lower temperature to a body of higher temperature.
flow from high to low
For an object to do work, it must possess what?
energy
What is the most work that can be done with 100 joules of energy?
100 J
Which of the following improves the efficiency of a machine?
A) reducing friction
B) adding more energy
C) running it faster
D) increasing friction
A) reducing friction
Which surface type absorbs the most heat?
white, black, or silver?
black
A child uses 25 N of force in order to move a toy car for a distance of 5m. How much work did he use?
125 J
A baseball bat, scissors, door on hinges, and your arms are all examples of what type of simple machine?
levers
Suppose you add the same amount of thermal energy to each of the following substances.
water specific heat = 1.00 c/g*C
ethanol specific heat = 0.584 c/g*C
gold specific heat = 0.031c/g*C
Which would undergo the largest change in temperature?
gold
The method by which heat can be transferred through a vacuum is ____________.
conduction
convection
natural radiation
thermal radiation
thermal radiation
The work a machine does for you is called the __________ work.
input or output?
OUTPUT
work that you do on a machine is called work input. The work done by the machine on an object is called work output.
In which class of levers is mechanical advantage always greater than 1?
2nd
The number of joules equivalent to 1.000 Btu’s is what?
1.000 Btu = 252.0 calories
1.000 calorie= 4.186 joules
Round to the neatest whole number.
1055 J
The temperature of 500. grams of ethanol is increased by 5.00° Celsius. What is the increase in the thermal energy of the ethanol?
(Specific heat of ethanol: 0.584)
1460 C
The efficiency of a modern bicycle is 95 percent. If you exert 200 joules in pedaling a bicycle on level ground, what is the work output?
190 J
A simple machine has an input force of 10 newtons and an output force of 100 newtons. What is the mechanical advantage of the simple machine?
10
Why does water act as a good coolant?
it has a high specific heat