Energy, Work, and Simple Machines Flashcards
Efficiency
Can be calculated by comparing a machine’s output work to its input work
Machine
A device that changes the magnitude or the direction of a force
Compound machine
Consists of 2 or more simple machines linked so that the resistance force of one machine becomes the effort force of the second machine
Resistance force
the force exerted by a machine
watt
a unit of power defined as 1 joule per second
effort force
the force exerted by a person on a machine
work-energy theorem
states that the work done on an object equals the change in kinetic energy of the object
energy
the ability of an object to produce a change in itself or its surroundings
kinetic energy
the energy that results from the motion of an object
power
the rate of doing work
mechanical advantage
the ratio of the resistance force of a machine to its effort force
why is gasoline called a ‘miracle’ in the film
Gas is relatively cheap, it leaves no ash or residue, has a high yield
joule
the SI unit used for work
ideal mechanical advantage
calculated by comparing the effort distance to the resistance distance
work
when an applied force is multiplied by the distance through which the force is applied
What makes electric cars still expensive
Batteries are expensive
What does the area under the force-displacement graph represent?
the work done on the object
what are 2 major advantages of natural gas as an energy source compared to the other fossil fuels
Natural gas is less expensive
environmental friendly; burns cleaner
What is the equation for finding work?
w = fd
Work and energy are measured in?
Joules
do you think nuclear power is a safe form of energy
it is very safe because they can withstand drastic weather and the plants are very secure
Explain the relationship between work and energy
Energy is the ability to do work. When you do work to move an object, you’re changing the object’s energy
What is the equation for finding power?
W/T or FD/T
Power is measured in?
Watts
Power can be described as..
the rate of energy transfer
In what unit is work measured?
Joules
what does the film say that you and I should do with the global energy demand
suggest nuclear, natural gas, and renewable energy be combined to see 50 year crossover.
Which of the following is NOT a way to increase power
increase time
why is the documentary called switch
because they are looking for ways to switch their prime,old fashioned energy sources to more environmental friendly and future ones
Which of the following would produce the greatest increase in the kinetic energy of a moving object?
doubling its velocity
what is not a part of the human body lever system
nerve fibers
A baseball and a ping pong ball are both shot from a slingshot with equal velocity. Which object has the greater velocity?
The baseball, it has a greater mass
A diver doing a somersault has a greater angular velocity in the
tuck position, is at more of an angle (i think..)
when you use a hammer to strike a nail, what class lever is this
first
How does the kinetic energy of a car traveling at 16 m/s compare with the kinetic energy of the same car traveling at 8 m/s?
it is 4 times greater (the velocity gets squared)
when you use a hammer t remove a nail using the claw, what class lever is this
third
machine
a device that changes the magnitude or direction of a force
energy
the ability of an object to produce a change in itself or its surroundings
How much work would have to be done on a truck with a kinetic energy of 2x10^4 J to reduce its kinetic energy by half
1 x 10^4
kinetic energy
energy that results from motion of an object
potential energy
energy of storage due to its position relative to other objects
A car has a kinetic energy of x J 7.5 s later it moves in the opposite direction with the same speed. What kinetic energy does it have?
xJ
power
the rate of doing work
hydrothermal and geothermal
this type of energy is created by hot spots; areas where earth’s core heat comes to surface
A car has a kinetic energy of x J 7.5 s later it moves in the opposite direction with 3 times its initial speed. What kinetic energy does it have?
9x, velocity is squared
A 6kg ball is travelling at 5m/s, what is its kinetic energy?
75 J
hydroelectric
if an area has flowing water and has the money to build a damn to connect it to the electricity grid, then they can use this form of renewable energy
If the velocity of the ball in question 16 doubles, its kinetic energy will be..
300 J
Biomass
This source can be made from scraps of plant, grain, wood, and other types of biological material; it converts a solid to a liquid form to use instead of gas in vehicles
nuclear energy
this type of energy relies o stellar energy; splitting of heavy atoms and the combining of lighter ones
Waves
This type of energy is produced when electricity generators are placed on the surface of the ocean. The energy provided is most often used in desalination plants, power plants, and water pumps.
wind turbines/ generators
this type of energy is used throughout areas of the midwest and in the southern regions of the U.S and can be a way to generate power to large areas in a fairly inexpensive way
Conventional Batteries
This source of energy is largely used for powering low voltage devices that are not used often. Its life and endurance is dependent on the apparatus it will energize and the chemical agent involved in its makeup
hydrogen fuel cells
this source is often compared to batteries; both convert the energy produced by a chemical reaction into usable electric power
Indirect Natural Gas
Converting landfill gasses into a source of renewable energy is beneficial because it reduces greenhouse-gas emissions and can generate revenue from the sale of the electricity
solar cells
this device absorbs light energy from the sun and converts it into usable forms of energy
Standard Electrical Power
This type of energy is significant because our society uses large amounts of it and it depends on the use of power plants that convert some other kind of energy into it.
