UNIT 4 5 6 7

Question 1

What is energy

Answer 1

amount of work done and measured in joules

Question 2

how does an object get energy

Answer 2

due to its motion or position

Question 3

what is the conservation of energy

Answer 3

energy cannot be created or destroyed when work is done, ENERGY IS CHANGED FROM FORM TO ANOTHER

Question 4

conservation of energy example

Answer 4

some energies are transformed from one form to another sometimes they transform into forms we do not want such as thermal or sound energy

Question 5

energy type

Answer 5

Kinetic energy, G.P.E
chemical energy, elastic potential energy, nuclear energy, internal energy,
electric energy, light, and sound

Question 6

kinetic

Answer 6

Due to motion =Car moving

Question 7

g.p.e

Answer 7

from potential fall= book shelf

Question 8

chemical

Answer 8

in chemical bonds =bonds in starch

Question 9

elastic potential energy

Answer 9

compress/stretch = streached elastic band

Question 10

nuclear

Answer 10

atoms rearrange /split= released in nuclear lant or uranium

Question 11

electrical

Answer 11

carried by electrons = battery to the bulb

Question 12

internal

Answer 12

motion of molecules =in a lass of water

Question 13

light

Answer 13

carried by light waves =from sun or lamp

Question 14

sound

Answer 14

carried in sound waves =from speaker

Question 15

calculate ke

Answer 15

1/2 mv<2>

Question 16

a van mass is 2000kg is travelling at 10 m/s.

calculate its kinetic energy if it increases by 20m/s by how much does it increase

Answer 16

step1: calculates vans ke at 10m/s
= 100,000 j / 1000 
=100kj 
step2: calculate vans ke at 20m/s 
= 400,000j/1000
=400kj 
step 3 :
400kj-100kj 
= 300kg

Question 17

gpe equation

Answer 17

=weight

x-height

Question 18

Example of conversion of energy

Answer 18

A book on a shelf has

g.p.e, if it falls off the shelf it will have k.e

Question 19

Efficiency

Answer 19

𝑬𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚 =
𝑼𝒔𝒆𝒇𝒖𝒍 𝒆𝒏𝒆𝒓𝒈𝒚 𝒐𝒖𝒕𝒑𝒖𝒕/
𝑬𝒏𝒆𝒓𝒈𝒚 𝒊𝒏𝒑𝒖𝒕
× 𝟏𝟎𝟎%

how much useful work is done with energy
supplied

Question 20

moment

Answer 20

turning effect of a force

M=f*d

Question 21

weight

Answer 21

mass*gravity /10/

Question 22

equilibrium

Answer 22

clockwise = anti clockwise

no resultant force and no reslutant moment

Question 23

Hooke’s law

Answer 23

f=ke

frorce= spring constant * extension

Question 24

the pressure of a solid

Answer 24

for per area

p=f/a

Question 25

liquid pressure

Answer 25

densitydepthacerleration due to gravity

Question 26

manometer

Answer 26

A manometer measures
the pressure difference.
• The height difference
shows the excess
pressure in addition to
the atmospheric
pressure.

Question 27

barometer

Answer 27

Tube with vacuum at the
top and mercury filling
the rest.
• Pressure of the air
pushes down on
reservoir, forcing
mercury up the tube.
• Measure height of
mercury
• ~760 mm of mercury is 1
atm.