READ THIS CAREFULLY AND COMPLETELY Physics Exam Instructions may talk to us abou
ID: 2075832 • Letter: R
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READ THIS CAREFULLY AND COMPLETELY Physics Exam Instructions may talk to us about the problems. You You may work together on this exam to solve problems. You class to may post on blackboard and ask about problems. You should not work with people outside of solve any problems solution should include motion diagrams and graphical representations as necessary. Solutions should be written clearly and concisely. It might be wise to include instructions at points in your solution. Very importantly you must write your own explanation describing the physics of the to the The is really appropriate to reference you solution in your essay independent. essay is to be your work alone. You should justify any assumptions and describe the these assumptions (if they are wrong or used for achieving a simple solution). You need not explain the physics. must include results in essay. We do not want to have to refer back to your work to get the answer. MUST STANDALONE! When talking about a situation, the associated pictures and diagrams must be there so that the reader need not jump around in the document. are trying to PLEASE the reader (also known as the grader). There will be the need to do some research to get masses of objects, reasonable sizes, coefficients of friction, etc. needed to solve a problem. Grading: All solutions will have the 30 second rule applied. The 30 second rule means that if the grader cannot figure out what you are doing in 30 seconds, you get a zero. Not drawing proper diagrams with proper labeling, inappropriate use of vector signs, and lack of units will get an additional 1 point per occurrence deducted. Specific Instructionsl Each question should be completed separately. Do not turn them in as a single packet. They are going to be separated by problem so make sure your name is on each and it includes the essay and your work attached. Remember, we do not grade the work. The essay stands alone! Essay's must be typed! You can hand draw and write in equations, figures etc, but everything else is to by typed. DO NOT have diagrams split over separate pages. e.g. force tables need to be on the same page as its associated diagram.Explanation / Answer
The ball travels horizontally after the launch at a height of 10m from water
let the horizontal vel - u
horizontal distance x = 300m
vertical height h = 100 m
h = gt2 /2 ; t = sqrt(2h/g) = sqrt(200/9.8)
within this time the ball has to travel 300 m horizontally
ut = 300
u = 300/t = 300/sqrt(200/9.8) = 66.41 m/s
The cannon ball has to be launched with a velocity of 66.41 m/s when it leaves the ramp
As the ball and the launcher moves through the incline the force on it are
1. frictional force - 0.2*mgCos(30)
2 gravitional force - mgSin(30)
length of the ramp = 100/sin(30)
work done agianst the forces = mg(Sin(30) +0.2(cos(30)) *100/Sin(30)
= 1.32 e+5 J
The sled has to move 10 m over plane now it will have only frictional force
frinctional force = 0.2mg
work done on the horizontal part - 0.2mg*10 = 2mg = 2*100*9.8
Total work done on the sled = 1.32e+5 + 1960 = 1.34 e+5 J
to get the velocity of u = 66.4 m/s
the sled must have a KE of = 0.5*100*66.42 = 2.20 e+5 J
Total energy to be given to the sled to launch = 2.20e+5 +1.34 e+5 J
= 3.54 e+5 J
This energy comes from the mass droping over 100 m of height
= m*9.8*100 = 3.54e+5
mass to be dropped m = 3.54e+5 /980 = 361.2 kg
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