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physics
Law of conservation of energy
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Cards (19)
What does the law of conservation of energy state?
Energy cannot be
created
nor
destroyed
What happens to energy according to the law of conservation of energy?
Energy changes form but remains
constant
Can energy be created or destroyed?
No
, it
cannot
be
created
nor
destroyed
What are the key concepts of the law of conservation of energy?
Energy can change
forms
Total energy remains
constant
Energy is not
created
or
lost
What is the definition of energy transformations?
Processes where energy changes
forms
How does a car engine demonstrate energy transformations?
Chemical energy
converts to
kinetic energy
What are the steps of energy transformation in a car engine?
Chemical energy from
petrol
to
heat energy
Heat energy to
kinetic energy
Some heat released as waste
What is a closed system?
A system that exchanges no
energy
Why is a closed system important for the law of conservation of energy?
It maintains constant
total energy
within
What defines a closed system in terms of energy exchange?
No energy enters or leaves
Total energy remains
constant
How does a thermos flask act as a closed system?
It prevents
energy exchange
with the environment
What happens to a ball rolling uphill in terms of energy?
Kinetic energy
changes to
potential energy
How does a light bulb demonstrate energy transformation?
Electrical energy
converts to light and
heat
What happens to chemical energy in burning wood?
It becomes
thermal energy
when burnt
What energy transformation occurs when charging a phone?
Electrical energy
converts to
chemical energy
What steps should you follow to solve energy-related problems using the law of conservation of energy?
Identify the
system
List
energy forms
involved
Write energy equation:
E
i
n
i
t
i
a
l
=
E_{initial} =
E
ini
t
ia
l
=
E
f
i
n
a
l
E_{final}
E
f
ina
l
Solve for
unknowns
What is the energy equation for a system?
E
i
n
i
t
i
a
l
=
E_{initial} =
E
ini
t
ia
l
=
E
f
i
n
a
l
E_{final}
E
f
ina
l
If a ball has 100 J of potential energy at the top of a hill, what is its final kinetic energy at the bottom?
100
J
What is the process to calculate final kinetic energy from potential energy?
Identify the
system
: Ball rolling down hill
List energy forms: Potential and kinetic
Write
energy equation
:
100
J
+
100\,J +
100
J
+
0
J
=
0\,J =
0
J
=
0
J
+
0\,J +
0
J
+
E
k
i
n
e
t
i
c
f
i
n
a
l
E_{kinetic\,final}
E
kin
e
t
i
c
f
ina
l
Solve:
E
k
i
n
e
t
i
c
f
i
n
a
l
=
E_{kinetic\,final} =
E
kin
e
t
i
c
f
ina
l
=
100
J
100\,J
100
J