Test #3 (Energy)

what statements are true according to the law of conservation of energy?

-energy cannot be created -energy cannot be destroyed -energy can be converted from one form to another

Turning off unused lights or appliances is an example of energy ____________________.

conservation

Doubling an object's velocity will double its kinetic energy.

false, quadruple

a toaster uses chemical energy to make toast

false, thermal

mass is measured in joules

false; energy

energy that is stored is kinetic energy

false; potential

The conversion of potential energy to kinetic energy follows the _________.

law of conservation of energy

in the equation E=mc^2, c is the speed of...

light

If the ________ of an object doubles, its kinetic energy doubles.

mass

A hammer falls off a roof top and strikes the ground with a certain kinetic energy. If it fell from a roof twice as tall, how would its kinetic energy compare? Explain.

the kinetic energy would be doubled

what increases when an object becomes warmer?

thermal energy

energy of an object increases when _____________ is done on the object

work

When an apple falls from a tree to the ground, the apple's beginning kinetic energy and ending gravitational potential energy are both equal to ____________________.

zero

Flat collector plates through which water flows are found in ____________________ solar energy systems.

active

Describe one energy conversion that takes place in a hydroelectric power plant.

as the river flows downwards at first, it's energy is potential then the gravitation potential energy is converted into kinetic energy

The law of ____ states that energy in a system can change forms but can never be created or destroyed

conservation of energy

You convert kinetic energy into thermal energy when you rub two sticks together because of _________

friction

______ can cause kinetic energy to change into thermal energy

friction

causes some mechanical energy to change to thermal energy

friction

an objects gravitational potential energy is directly related to

mass and height

a carpenter lifts a 10 kg piece of wood to his shoulder 1.5 m above the ground. he then sets the wood on his truck at 1 m above the ground and makes his delivery going 10 m/s. why is the kinetic energy of the lumber higher on the truck during the delivery than when it drops from the carpenter's shoulder?

the truck is moving at a higher velocity

the total potential energy and kinetic energy of all the microscopic particles in an object make up its

thermal energy

Why can you model the thermal energy of an object as the "mechanical energy" of the particles that make it up?

thermal energy is both kinetic and potential

chemical potential energy is energy stored in chemical bonds

true

friction causes some mechanical energy to change to thermal energy

true

mechanical energy is the total amount of potential and kinetic energy in a system

true

the greater mass a moving object has, the more kinetic energy it has

true

Energy in the form of motion is potential energy.

False, kinetic

You can calculate an object's gravitational potential energy by using the equation

GPE=mgh

SI unit of energy

Joule

thermal energy is measured in...

Joules

explain why a more streamlined car generally will have better fuel economy than a bulkier car that has the same mass.

Less air resistance and friction, which causes heat, therefore less loss to heat energy

Why is the gravitational potential energy of an object 1 meter above the moon's surface less than its potential energy 1 meter above Earth's surface?

The object's acceleration due to gravity is less on the moon.

explain how biomass energy depends on the sun.

biomass energy is the chemical energy stored in living things. The chemical energy is produced as plants converted sunlight in the form of electromagnetic energy and chemical energy.

what are examples of objects with elastic potential energy

bow and arrow

nutritionists use the ___ to measure how much energy we get from foods

calorie

unit used to measure energy in food

calorie

mechanical energy does not include kinetic energy or _________ energy

chemical

Walking converts what type of energy into mechanical energy?

chemical energy

the energy stored in gasoline is

chemical energy

energy cannot be created or destroyed" is a statement of the law of

conservation of energy

the law of ______________________ states that energy cannot be created of destroyed

conservation of energy

The total energy of a system remains

constant

the process of changing energy from one form to another is called energy

conversion

When a pole-vaulter flexes the pole, the pole-vaulter increases the pole's ____________________ potential energy.

elastic

thermal energy is energy stored by things that stretch or compress

elastic potential

energy stored by things that stretch or compress

elastic potential energy

what energy conversion that takes place as an arrow is shot from a bow?

elastic potential energy

Nuclear power plants are designed to convert nuclear energy into what type of energy?

electrical energy

Work is a transfer of

energy

the ability to cause change

energy

what is transferred by a force moving an object through a distance?

energy

two copies of the same book are in a book case. one book is twice as high as the other. they have the same potential energy.

false, different

When a plant falls from a window its thermal energy is transformed into kinetic energy.

false, potential

a rock at the edge of a cliff has kinetic energy because of its position

false, potential

identify two types of nuclear reactions in which the equation E=mc^2 applies.

fission and fusion

an orange in a tree has _____________ energy due to earth pulling down on it

gravitational potential

energy stored by things that are above earth

gravitational potential energy

why might a consumer buy a more energy-efficient refrigerator even though it may cost more than a conventional refrigerator?

it uses less energy due to efficiency, so over time, it will save money

Energy and work are measured in the SI unit called the

joule

energy cannot be created or destroyed

law of conservation of energy

the potential energy of an object depends on its

mass and height

what are two examples of nonrenewable energy resources?

oil and coal

what is a characteristic of a renewable energy resource?

they can be easily regenerated

what are two examples of renewable energy resources?

wind turbines and solar energy

If no friction acts on a diver during a dive, then what is true about the mechanical energy of the diver?

(KE+ PE)beginning = (KE + PE)end

show that the unit "kg x m^2/s^2", calculated from the kinetic energy equation, is equivalent to a joule

kg x m^2/s^2 = joule

Wind turbines convert ____________________ energy into electrical energy.

kinetic

a car engine changes chemical potential energy into the ____ energy of the moving car

kinetic

what are the two general types of energy that can be used to classify many forms of energy?

kinetic and potential energy

energy in the form of motion

kinetic energy

the energy of motion is called

kinetic energy

the mechanical energy of an object equals its

kinetic energy plus its potential energy

what is used to calculate potential energy?

mass, gravitational accleration, and height

what is used to calculate kinetic energy?

mass, weight, and velocity

the sum of the kinetic energy and potential energy of an object is called its ________ energy

mechanical

the total amount of kinetic and potential energy in a system

mechanical energy

geothermal energy, in addition to being renewable, offers the benefit of being...

nonpolluting

energy resources that exist in limited amounts and, once used, cannot be replaced except over the course of millions of years are called ________ energy resources

nonrenewable

All energy can be considered as kinetic energy, ____________________ energy, or the energy in fields.

potential

Mechanical energy is the total kinetic and _____ energies in a system.

potential

energy that is stored due to position or shape is called _________ energy

potential

the _____ energy of an object increases with its height

potential

stored energy due to position

potential energy

the gravitational potential energy of an object is always measured relative to

reference level from which the height is measured

The mechanical energy of a coconut falling from a tree _____

remains constant

Solar cells convert what type of energy into electrical energy?

solar energy

the kinetic energy of an object is proportional to the square of its

speed

in what two ways can you increase the elastic potential energy of a spring?

stretch or compress

A book and a feather sitting next to each other on a shelf have different potential energies.

true

the law of conservation of energy states that although energy can change forms it never be created of destroyed

true

The kinetic energy of an object increases as its _____ increases

velocity

the amount of kinetic energy a moving object has depends on its mass and its

velocity

what is the most familiar form of electromagnetic energy?

visible light

what evidence is there that energy is transferred as a golf club does work on a golf ball?

when you raise the club you have potential energy. as the club hits the ball kinetic energy is shown as the ball moves

a carpenter lifts a 10 kg piece of wood to his shoulder 1.5 m above the ground. he then sets the wood on his truck at 1 m above the ground and makes his delivery going 10 m/s. What is the wood's potential energy on the carpenter's shoulder and on the truck?

(a) shoulder-147 J (b) truck-98 J

a carpenter lifts a 10 kg piece of wood to his shoulder 1.5 m above the ground. he then sets the wood on his truck at 1 m above the ground and makes his delivery going 10 m/s. if the wood drops from the carpenter's shoulder, what would its maximum kinetic energy be?

147 J

use the equation KE=1/2m x v^2 to calculate the kinetic energy of a 100 kg cart moving at a speed of 7 m/s?

2450 J

a 12 kg sled is moving at a speed of 3 m/s. at what speed will the sled have twice as much kinetic energy?

4.25 m/s (???)

a carpenter lifts a 10 kg piece of wood to his shoulder 1.5 m above the ground. he then sets the wood on his truck at 1 m above the ground and makes his delivery going 10 m/s. what is the wood's kinetic energy during the delivery?

500 J

a 4 kg cat is resting on top of a bookshelf that is 2 meters high. what is the cat's gravitational potential energy relative to the floor if the acceleration due to gravity is 9.8m/s^2

78 J

the kinetic energy of the pendulum bob in figure 15-1 increases the most between locations

B and C

in figure 15-1, the kinetic energy of the pendulum bob decreases between locations B and...

D

Green plants convert light energy from the sun into _____

chemical potential energy

energy stored in chemical bonds

chemical potential energy

the energy stored in foods and feuls is

chemical potential energy

a small 30 kilogram canoe is floating downriver at a speed of 2 m/s. what is the canoe's kinetic energy?

60 J

use the equation GPE= m x 9.8 m/s^2 x h to calculate the gravitational potential of a 10 kg sack of groceries on a shelf 1m off the floor.

98 J