work power and energy

Question 1

energy is a vector quantity
true or false

Answer 1

false

Question 2

energy is needed to do —–

Answer 2

mechanical work

Question 3

energy conversions occur during

Answer 3

work done

Question 4

energy is measured in

Answer 4

joules

Question 5

formula of energy

Answer 5

e=mc2

Question 6

energy can be stored as

Answer 6

chemical energy
elastic energy
potential energy

Question 7

chemical energy used in

Answer 7

cells

Question 8

solar energy used in

Answer 8

solar panels

Question 9

nuclear energy used in

Answer 9

atomic bomb

Question 10

potential energy (definition)

Answer 10

energy due to change in position of an object

Question 11

kinetic energy (definition)

Answer 11

energy due to motion of an object

Question 12

difference between kinetic and potential energy

Answer 12

kinetic energy is the energy due to its motion
potential energy is a stored form of energy due to its size and shape of the object

Question 13

examples of kinetic energy

Answer 13

winds have kinetic energy
a sppining frisbee has kinetic energy
a rolling soccer ball also has kinetic energy

Question 14

types of potential energy(also define them)

Answer 14

elastic potential energy: due to shape and size
gravitational potential energy : whenever there is a change in height of an object

Question 15

the formula of kinetic energy and gravitational energy

Answer 15

KE: 1/2 MV2
GPE:MGH

Question 16

definition of power(in terms of work done)

Answer 16

rate of doing work

Question 17

definition of power ( in terms of energy)

Answer 17

rate of transfer of energy

Question 18

formula of power

Answer 18

energy/time

Question 19

power measured in

Answer 19

watts

Question 20

definition of work done

Answer 20

Work done by a constant force on an object is the product of force and distance made by the direction of force

Question 21

formula of work done

Answer 21

force multiplied by direction of force

Question 22

unit of work done

Answer 22

NM

Question 23

work done is not done when

Answer 23

work is not done when the object doesn’t move in the direction of the force

Question 24

why does energy has the same unit as work done

Answer 24

because work done is equal to energy transformed

Question 25

unit of work done

Answer 25

joules

Question 26

principle of conversion of energy

Answer 26

energy can't be made or destroyed but it changes forms

Question 27

what is efficiency

Answer 27

it is the ratio of useful energy (work done) over input energy

Question 28

formula of efficiency

Answer 28

output energy multiplied 100/input energy

Question 29

efficiency is measured in

Answer 29

percentt

Question 30

why does efficiency have no unit

Answer 30

because it is a ratio of two quantities

Question 31

not all energy is transferred into useful energy part of it is transferred into

Answer 31

heat loss (fusion)

Question 32

define renewable energy resources

Answer 32

renewable energy sources that can be replenished over a short period

Question 33

define non renewable sources of energy

Answer 33

non-renewable sources of energy sources are energy sources that can't be replenished over a short period

Question 34

state examples of renewable sources of energy

Answer 34

solar energy, wind energy, hydro-energy, geothermal energy

Question 34

state examples of renewable sources of energy

Answer 34

solar energy, wind energy, hydro-energy, geothermal energy

Question 35

state examples of non-renewable sources of energy

Answer 35

coal, fossil fuels, nuclear fuels

Question 36

explain solar energy

Answer 36

solar energy is the energy from the sun, the sun is a big ball of heat and light resulting from nuclear fission at its core. the nuclear reaction releases energy that travels outward to the surface of the sun

Question 37

explain solar panels

Answer 37

solar panels absorb energy from the sun and converted it into electrical energy most solar energy is collected through photovoltaic cells, typically made of silicon that acts as a semiconductor. the sun's rays contain heat and radiation. when the rays hit the surface of the silicon cells, they cause a release of electrons that roam freely

Question 38

in a solar panel heat energy from the sun turns into

Answer 38

electrical energy

Question 39

in the block diagram of solar panel solar panel into

Answer 39

transformer

Question 40

state the advantages of solar panel

Answer 40

low running cost no major pollution it is a renewable energy

Question 41

state the disadvantages of solar panel

Answer 41

low efficiency covers a large area availability varies amount of current produced by solar cells is usually too small to power devices that need a large amount of electricity

Question 42

explain wind turbines

Answer 42

wind turbines convert the kinetic energy in the wind into mechanical power. the generator in the wind turbine can convert this mechanical into electricity

Question 43

explain geothermal energy

Answer 43

geothermal energy is a type of renewable energy taken from the earth's core. it comes from the heat generated during the original formation of the planet and the radioactive decay of materials. this thermal energy is stored in rocks and fluids in the center of the earth

Question 44

explain hydroelectric energy

Answer 44

river and rainwater fill up a lake behind the dam. water rushes down from the lake and spins the turbine. the turbine connected to the generator, when the turbine rotates generator also rotates and produces electricity

Question 45

explain fossil fuel/coal power station

Answer 45

in thermal energy stations, electricity is produced by burning non-renewable energy sources (like coal, and natural gas) as a fuel for the generation of heat energy by burning it. as the heat energy is transferred into the boiler the water in the boiler starts to boil and evaporate the high pressurized steam passes to the turbine and it rotates, as a result, the generator is turned on and produce electricity. once the steam has passed through the turbines, it is cooled and condensed(turned back into a liquid) so that it can be fed back to the boiler, and the process repeats

Question 46

explain nuclear fission

Answer 46

nuclear fission is the splitting of a heavy nucleus into two lighter nuclei when the nucleus of an atom is bombarded with a neutron the energy of the neutron causes the target nucleus to split into two (or more) nuclei that are larger than the parent nucleus, releasing a large amount of energy during the process

Question 46

explain nuclear fission

Answer 46

nuclear fission is the splitting of a heavy nucleus into two lighter nuclei when the nucleus of an atom is bombarded with a neutron the energy of the neutron causes the target nucleus to split into two (or more) nuclei that are lighter than the parent nucleus, releasing a large amount of energy during the process

Question 47

explain nuclear fusion

Answer 47

nuclear fission is the combining of two lighter nuclei to form a heavier nucleus, releasing a vast amount of energy during this process. nuclear fusion is believed to be the process by which energy is released by the sun. when the two hydrogens -2 nuclei moving at high speed collide, they can join together to produce a heavier nucleus(helium). a large amount of energy is released

Question 48

explain the wind energy

Answer 48

wind power or wing energy describes the process by which the wind is used to generate mechanical power or electricity, wind turbines convert the kinetic energy in the wind into mechanical power

Question 48

explain the wind energy

Answer 48

wind power or wing energy describes the process by which the wind is used to generate mechanical power or electricity, wind turbines convert the kinetic energy in the wind into mechanical power