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Chapter 4
DHS PS Ch. 4 - Work and Energy (2015)
Question | Answer |
---|---|
Energy has the ability to ___________ ? | cause change |
What 2 factors determine how much kinetic energy an object has? | speed and mass |
A glass sitting on the edge of a table is an example of what kind of energy? | potential or GPE |
A ball rolling across the floor is an example of what kind of energy? | kinetic |
Energy stored in chemical bonds is? | chemical potential energy |
What two factors determine how much gravitational potential energy is in an object? | weight (mass x gravity) of the object and height above the ground |
Energy in the form of motion is what kind of energy? | kinetic |
What is the formula for calculating kinetic energy? | 1/2mv2 |
What is the SI unit used to measure energy? | Joule |
What is the abbreviation for Joules? | J |
Energy stored in a motionless object | potential |
Energy stored by things that stretch or compress is what kind of energy? | elastic potential energy |
Energy stored in chemical bonds between atoms is what kind of energy? | chemical potential energy |
Energy stored by things that are above Earth's surface is what kind of energy? | gravitational potential energy |
What is the abbreviation for gravitational potential energy? | GPE |
The amount of GPE an object has depends on what 3 things? | mass, the acceleration due to gravity, and its height above ground |
What is the formula for calculating GPE? | mgh |
What kind of energy does food provide for your body? | chemical potential energy |
As energy transformation occur within a system, the total energy of the system must ________? | remain constant |
During energy transformations, energy is never ________ . | created or destroyed |
A baseball is hit into the air with a bat. When does the baseball have the greatest gravitational potential energy? | when it reaches its highest point |
The law of conservation of energy states that? | energy cannot be created or destroyed |
In what units are food energy measured in? | calories |
Is friction a form of energy? | No |
Is thermal a form of energy? | Yes |
Is electrical a form of energy? | Yes |
Is chemical a form of energy? | Yes |
Why isn't all the chemical potential energy found in gasoline transformed into mechanical energy? | because of friction between many moving parts |
What is it called with energy is changing from one form to another? | energy conversions or transformations |
What form of energy do fuels store energy in? | chemical potential energy |
The total amount of potential and kinetic energy in a system is called? | mechanical energy |
Energy may change from one form to another, but the total amoung of energy never changes is called? | Law of Conservation of Energy |
As a swing moves back and forth, its energy continually converts from kinetic to potential and back is an example of? | The Law of Conservation of Energy or mechanical energy |
Friction converts some of the mechanical energy into? | thermal energy |
Let's say 1,000,000 J of gas were added to a car. When all the gas was burned, only 250,000 J of energy was transformed to KE. Was energy lost? | No, energy is always conserved. When a car burns gasoline, only some energy is changed to kinetic energy due to friction. |
What is it called when the transfer of energy that occurs when a force makes an object move? | work |
Picking up a stack of dishes from the table is an example of? | work |
When work is done, there is always a ______ __ _______? | transer of energy |
What is the rate at which energy is transferred or work is done? | power |
Power is measured in? | watts |
A watt is equal to? | one joule per second |
What do we call the transer of energy that occurs when a force makes an object move? | work |
For work to occur, an object must? | move |
The motion of the object must be in what direction as the applies force on the object? | the same direction |
Energy is always ___________ from the object doing the work to the object on which the work is done. | transferred |
Work is done on an object when a ______ is being applied to the object and the object moves. | force |
When calculating work, work equal force (in newtons) times ______. | distance |
The amount of work done in a certain amount of time is called? | power |
A rate at which energy is transformed is called? | power |
To calculate power, power equal? | work divided by time |
Power is measured in? | watts |
How are energy and work related? | Energy is transferred from an object doing work to an object being worked on |
The kinetic energy of an object increases as its _____ increases. | velocity |
Increasing the speed of an object _____ its potential energy. | does not affect |
The SI unit for energy is the? | Joule (J) |
Does an upright piano make use of electrical energy? | No |
Does a radio make use of electrical energy? | Yes |
Does a toaster make use of electrical energy? | Yes |
Does a digital camera make use of electrical energy? | Yes |
A bus engine transfers chemical potential energy into _____ so that the bus moves. | kinetic energy |
According to the law of conservation of energy, the total amount of energy in the universe ______? | remains constant |
The transfer of energy to a body by the application of force that caused the body to move in the direction of the force is called? | work |
What is defined as the rate at which work is done? | power |
As a dropped penny falls toward the ground, _________ energy is converted to _____ energy. | potential, kinetic |
As a fly ball is hit in the air, ________ energy is converted to ________ energy. | kinetic, potential |
A dropped tennis ball will not return to its original position because? | some of the mechanical energy is converted to nonmechanical energy |
The law of conservation of energy states that energy? | cannot be created or destroyed |
Mechanical energy can change to nonmechanical energy as a result of? | friction |
What are the units of power? | watts |
A baseball is hit into the air with a bat. When does the baseball have the greatest kinetic energy? | when it leaves the bat |
When work is done, there is always a? | transfer of energy |
If a car quadruples its velocity, how does it affect its KE? | it is 16 times greater |
If a car doubles its velocity, how does it affect its KE? | it is 4 times greater |
If a car triples its velocity, how does it affect its KE? | it is 9 times greater |
If an object doubles its height, how does that affect its GPE | it is doubled |
How doe the rate at which you climbed the stairs affect your work? | time is not a component of work so it had no effect. |
How doe the rate at which you climbed the stairs affect your power? | the faster work is completed, the more power is exerted. |
Where is the kinetic energy the greatest at on a roller coaster | at the bottom of the first hill (it is the lowest point usually) |
On a roller coaster, can there be any higher point than the first hill? | No, not unless extra energy is added to the system (like the Maverick) |
Carrying a pumpkin, work or nonwork? | nonwork (force is up while pumpkin does not) |
Setting a plate down, work or nonwork? | nonwork (force is up while plate goes down) |
Shutting a door, work or nonwork? | work (force and direction are same) |
Pulling a wagon, work or nonwork? | work (force and direction are same) |
A slap shot in hockey, work or nonwork? | nonwork (puck no longer in contact with stick) |
What is the formula to determine the Power rating of an electrical device? | P = E/t |
Who is more powerful? Sally does 20 J in 10 s while Jenny does 10 J in 10 s. | Sally is twice as powerful (2 W vs. 1 W) |