Transcript Energy 1 with lab

Warm Up
2/8/08
1) How much work is done when a
7 N force is applied to a box to
move it 7 m?
2) Define Energy, and use it in a
sentence.
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Standards
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Go over Quiz
Review
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Work: Remember work is force
times distance.
Another definition for work: Change
in kinetic energy (K)
Kinetic Energy = ½ mv
2
Lab
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1) Gather materials
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Mass Cart, meter stick, paper, mass equal to the
mass of the cart, Masking Tape, Stopwatch,
pencil, Wood Board
2 Ring Stands
2) Measure 0.5 m and put tape where you
started and ended
3) Make a ramp with your board, tilt it at 20
degrees
4) Start the front of your cart at a HEIGHT
(NOT distance up ramp) of 10 cm. Release it
and time how long it takes to travel the ½ m
marked in tape.
Lab
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5) Record this time and use it to find the
velocity of the cart on level ground.
6) Repeat 3 times (and record)
7) Repeat 4, 5, & 6 for a Height of 20 cm
8) Repeat 3, 4, 5, 6, & 7 for an angle of 35
degrees,
9) Repeat all of the steps after adding
enough mass to the cart to double its total
mass
10) record the mass of the cart alone, and
twice its mass, and find the kinetic energy for
each trial.
Examples
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1. A 2 kg bird is flying at 25 m/s, what is the
bird’s kinetic energy?
2. A 1000 kg car is traveling at 10 m/s, what
is the car’s kinetic energy?
3. A 600 kg ostrich goes from traveling 10
m/s to 5 m/s, what is the change in the
ostrich’s kinetic energy?
4. If a 2 kg object has 100 J of work done on
it. How much will its velocity change?
Practice
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1. A 7 kg bird is flying at 15 m/s, what is the
bird’s kinetic energy?
2. A 2000 kg car is traveling at 13 m/s, what
is the car’s kinetic energy?
3. A 400 kg emu goes from traveling 3 m/s to
7 m/s, what is the change in the ostrich’s
kinetic energy?
4. If a 9 kg object has 400 J of work done on
it. How much will its velocity change?
Homework
pg 267
 (1, 5, 7, 17-19, 36-39, 52)
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