Rube Goldberg Machine - Task

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30 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

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April 22, 2013
Rube Goldberg Machine - Task
The basic objective is to:
1.
Take a simple task, and make it as complicated as possible. For some examples of what a
Rube Goldberg Machine is, and some historical background, check out the following link:
<http://www.rube-goldberg.com/>
2.
For the SPH 3U1 course, your lab group must do a
physics
Rube Goldberg Machine. Your project
must include elements from 5 of the 6 major strands of physics covered in this course:
1. kinematics and dynamics
2. gravitation and friction
3. energy, work, heat and power
4. vibration and waves
5. optics/light
6. electricity and magnetism
3.
A formal group write-up must accompany your setup and must include the following:
a)
A title page including the participants’ names, your project title, the instructor’s
name, the date, and course code.
b)
A statement of what your machine is supposed to do - e.g. “turn on a light bulb”.
c)
A parts list for your machine. (# if individual pieces as well - e.g. 45 dominoes)
d)
A “play-by-play” detailing what actually happens during the operation of your machine
including the energy transformations, and the specific strand of physics involved at each
step of your machine.
e)
A list of the 6 major strands and one step in which each was incorporated.
f)
A printout of the
Rube Goldberg Machine Rubric
for marking purposes.
4.
General Guidelines:
i)
For a lab group collaboration, aim for at least 30 steps.
ii)
Use your imagination. Novel ideas incorporated into the design will improve evaluation.
iii)
The machine and all the materials must be removed at the end of the day. (see rubric for
marking)
iv)
Participation of each group member is a must. Adjustments in individual marks will be
made if a student
“doesn’t pull his or her weight”
.
5. Machine Presentation
The team will have 2 attempts to complete the task without help. Each team member will be
responsible for presenting the “play-by-play” of their share of the overall without reading from the
notes.
In addition
to energy changes comments regarding forces and Newton’s Laws are
expected.
(Individual marks are awarded for this section per the rubric)
http://www.youtube.com/watch?v=tkzr0naZnZ0
April 22, 2013
April 22, 2013
April 22, 2013
Energy Transformation - Additional Problems
1.
A ball is dropped from 10. m above the ground.
Using energy calculations, determine the speed of
the ball at 4.0 m above the ground.
2.
Determine the height of a roller coaster hill which
has a car speed of 4.5 m/s if the height of the
starting hill is 45 m and the car has an initial speed
of zero.
April 22, 2013
Energy Transformation Problem - Pile Driver
The ram of a pile driver has a mass of 1000. kg. It falls 4.55 m onto a
pile, and then drives the pile 15.0 cm into the ground. Find the
average force the ram exerts on the pile.
April 22, 2013
Energy Transformation Review
1.
A pendulum 1.0 m long is pulled aside to the position where the bob has been raised
vertically a distance of 10. cm. If the bob has a mass of 100. g, calculate:
a) the potential energy of the bob before release
b) the kinetic energy of the bob at its lowest position
c) the velocity of the bob at the lowest position
2.
When construction firms wreck old buildings, a large pendulum arrangement is
frequently used. If the ball of the equipment suspended on a cable has a mass of
1000. kg and is raised 3.0 m vertically when it is pulled to one side, calculate:
a) the kinetic energy of the ball as it strikes the building
b) the speed of the ball on impact
3.
On the midway, you can win a prize if the bell rings when you strike a wooden
block with a 10.0 kg hammer. The block is at one end of a lever, the other end
of which drives a metal bar of mass 2.0 kg up a slide to ring the bell 9.0 m
above. With what speed must the hammer strike the block in order to make the
bar hit the bell?
4.
Jack and Jill were in a roller coaster car. The car was released at a height of
100. m. The total mass of Jack, Jill and the car was 1000. kg. After roaring up
and down and around tight bends, their speed at a certain point was 28 m/s.
What is their height at this point?
5.
A 2.0 kg object rolls down an incline 20. m high with an initial speed of 5.0 m/s.
Calculate the speed of the object at the bottom of the incline assuming no energy loss
due to friction. Provide a sketch with your solution.
6.
Jill can apply a force of 20. N to the peddles of her bicycle. Jill starts riding her
bicycle and peddles 200. m and she reaches a speed of 25 km/h. She then stops
pedalling and coasts for 200. m.
a) How much work did she do in the first 200. m?
b) How much work is Jill doing while she coasts the 200. m?
ANSWERS: 1.(a) 0.098 J (b) 0.098 J (c) 140 cm/s
2. (a) 2.9 x 10
4
J (b) 7.7 m/s
3. 5.9 m/s
4. 60. m
5. 20.m/s
6. (a) 4.0 x 10
3
J
(b) 0
April 22, 2013
April 22, 2013
Some children go tobogganing on an icy hill. They start from rest at the top of the hill
as shown. The toboggan and children have a combined mass of 90.kg. If the friction
is small enough to be ignored, determine:
a) the total mechanical energy of the toboggan at A.
b) the speed of the toboggan at B.
c) the speed of the toboggan at C.
Additional Transformation of Energy Problems
1.
2.
A boy fires a 60.g pebble with his slingshot. the pebble leaves the slingshot at

35 m/s.
a) How high above the slingshot will the pebble rise if it is fired straight up?
b) If the pebble is fired so that it goes in an arc and has a speed of 10.m/s at
its maximum height, what will the maximum height be?
c) At what speed would an 80.g pebble have to be fired to reach the same
height as the pebble
in (a).
April 22, 2013
April 22, 2013
Efficiency Problem
An electric motor uses 7.5 x 10
6
J of electrical energy to do 6.4 x 10
6
J of
work. What is the efficiency of the motor?
April 22, 2013
Investigation 1 – Page 220
Informal Lab
Marking Scheme
Title Page
1
Purpose
1
Table
8

Analyzing &
interpreting 1-3
3
Concluding &
communicating
4-7, 9
5
Total
18
Notes & Changes:
a) Run 4 trials with h = flat, ~12 cm, ~25 cm, ~37 cm
b) Spring scale marked with “g”; change to “N” by dividing reading by

1000 & multiplying by 9.8 m/s/s.
(1 set of sample calculations)
April 22, 2013
April 22, 2013
April 22, 2013
POWER:

RATE OF USING ENERGY
POWER =

and
P = VI

THE COST OF CURRENT ELECTRICITY
Power companies charge consumers for the energy used.
Rearranging the power equation to determine energy:

E = Pt
If we know the power rating (in kilowatts) of an appliance and the time (in hours) it is
used, we can find the energy consumed. (in kWh)
If we know the dollar value of energy per kWh, the cost of energy can be determined
using the equation:
Cost = Energy used x Rate (e.g. 10 cents per kWh)

April 22, 2013
Cost of Electricity Example
1. Calculate the cost of running a refrigerator for 24 hours if the
power rating of the refrigerator is 0.78 kW.
2. Calculate the cost of running your toaster for a total time of 1.5 h if
the voltage supply to your house is 120 V and the current is 8.5 A.
April 22, 2013