Download Physics Exam Review – Science 10 Define heat and temperature

Physics Exam Review – Science 10
1. Define heat and temperature
Heat: Transfer of thermal energy from one object to another
Temperature: average kinetic energy if the particles in a substance
2. Write (in your own words) the first and second law of thermodynamics.
First law: energy cannot be created or destroyed
Second Law: No process (energy conversion) can be 100% efficient. Some energy is always lost
as heat
3. Fill in the following chart:
Quantity
Scalar/Vector?
Work
Vector
Distance
Scalar
Units
J
Formula
W = Fd
W
d
m, cm, etc.
d = d1 + d2…
Vector
D
m, cm, etc.
d = d 2 – d1
m/s
v = d/t
Velocity
Scalar
Vector
v
v
m/s
v = (d2-d1)/t
Acceleration
Vector
a
m/s2
a =( v2 – v1)/t
Displacement
Symbol
Speed
4. Solve the following problems. Remember to round to the correct number of significant digits!
a. How much work is done lifting a book 2.0 m with 45 N of force?
=90 J
b. A horse runs 100 m (South) in 8.0 s. What was its velocity?
= 13 m/s, south
c. You walk 15.0 m North and then 2.5 m south in 120 s. What was your displacement AND
speed?
d = 12.5 m, North
v = 0.15 m/s
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d. A car reaches a velocity of 100 m/s in 9 s. What was the car’s acceleration?
= 1 x 101 m/s
5. Fill in the following chart:
Quantity
Definition
Kinetic Energy
Energy of
motion
Potential Energy
Stored energy
Efficiency
how efficient a
system is at
converting
energy from one
form to another
Symbol
Ek
Units
J
Formula
Ek = ½ mv2
Ep
J
Ep = mgh
e
None: it’s a
ratio (percent)
= output/input x
100
6. Solve the following problems. Remember to round to the correct sig digs!
a. What is the kinetic energy of a 1000 kg car moving at 13 m/s?
= 8.5 x 104 J
b. A 0.30 kg baseball has 54 J of energy. What is its speed?
= 19 m/s
c. How much potential energy does a 0.50 kg book have sitting on a shelf 3.0 m high?
= 15 J
d. You drop a penny from a 150 m tall building. What is its speed at the bottom?
= 54.2 m
2
e. An electrical generator uses 50 J of energy to produce 2 J of electricity. Calculate the
efficiency.
=4%
f.
You are pushing a box filled with books across a floor. If you did 322.5 J of work by pushing
the box a distance of 4.3 m, what force did you exert?
= 75 N
g. Homer’s car broke down, and he needs to push it home to Evergreen Terrence. If he pushed
the car 570 m, with a force of 780 N, how much work did he do?
= 4.45 x 105 J
h. On a recent trip to Africa, you have a ticked off a baby hippopotamus, and it starts to run at
you with a speed of 12 m/s. If the hippopotamus has a mass of 780 kg, what is it’s kinetic
energy?
= 5.6 x 104 J
i.
A 15 kg child is sliding down a playground slide. If the child’s kinetic energy is 77 J, how fast
is the child sliding?
= 3.2 m/s
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j.
A mountain lion is sitting in a tree 7.5 m above the ground. If the mountain lion has a mass
of 545 kg, what is it’s gravitational potential energy?
= 4.0 x 104 J
k. A boulder rests on a ledge 36 m above a lake. If it has 2.8 x 105 J of potential energy relative
to the lake surface, what is the mass of the boulder? If it falls, what will be its velocity as it
hits the water?
= 7.9 x 102 kg
l.
4500 N of force is required to stop a car with a mass of 1600 kg. If the car is traveling at a
speed of 15 m/s, what is it’s stop distance?
= 40 m
m. A roller coaster raises its passengers a vertical distance of 42.1 m above the ground. If the
total mass of the coaster and passengers is 5.27 x 103 kg, what is …
a. The gravitational potential energy?
= 2.18 x 106 J
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b. The speed of the roller coaster once it drops?
= 28.7 m/s
n. Name three types of potential energy.
Chemical, elastic, gravitational, nuclear
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