1.)This question requires a numeric or algebraic answer. In order to receive full credit for this problem
you must show all your work. To show your work for this problem you may scan neatly handwritten
work or type up your work in MS Word using the equation editor and submit it using the Midterm Exam
Dropbox. You should make your submissions after you complete the exam.
A 750 g aluminum pan is removed from the stove and plunged into a sink filled with 10.0 liters of water
at 20.0° C. The water temperature quickly rises to 24.0° C. What was the original temperature of the pan
in degrees Celsius and degrees Farenheit?
Specific heat of aluminum = 0.9J/gm/K =0.215 cal/gm/K
If t deg C was pan temperature, heat given by pan = 750*0.215*(t-24)
Heat taken by water = 10*1000*1*(24-20)
Hence, 750*0.215*(t-24) = 10*1000*1*(24-20)
Or, t = 272.06 deg C
We have C/5 =( F-32)/9. Putting C = 272.06, we get F = (9*272.06/5)+32 = 489.711 degF
2.)This question requires a numeric or algebraic answer. In order to receive full credit for this problem
you must show all your work. To show your work for this problem you may scan neatly handwritten
work or type up your work in MS Word using the equation editor and submit it using the Midterm Exam
Dropbox. You should make your submissions after you complete the exam.
An electric generating plant boils water to make high-pressure steam. The steam spins a turbine that is
connected to the generator. How many liters of water must be boiled to fill a 5.0-cubic-meter boiler
with 50 atm of steam at 400° C? The steam pressure has dropped to 2.0 atm at 150° C as the steam exits
the turbine. How much volume does it now occupy?
3.)This question requires a numeric or algebraic answer. In order to receive full credit for this problem
you must show all your work. To show your work for this problem you may scan neatly handwritten
work or type up your work in MS Word using the equation editor and submit it using the Midterm Exam
Dropbox. You should make your submissions after you complete the exam.
What is the frequency of blue light that has a wavelength of 450 nm? What is the frequency of red light
that has a wavelength of 650 nm? What is the index of refraction of a material in which the red light
wavelength is 450 nm?
Speed of light = 3*108m/sec
Velocity = wave length * frequency
Hence, frequency of blue light = 3*108/450*10-9 =6.67*1014 Hz.
Frequency of red light = 3*108/650*10-9 = 4.815*1014 Hz.
Index of refraction that changes a wavelength of 650 nm to a wavelength of 450 nm = ratio
of the wavelengths.
Hence, index of refraction = 650/450 = 1.44
4.)This question requires a numeric or algebraic answer. In order to receive full credit for this problem
you must show all your work. To show your work for this problem you may scan neatly handwritten
work or type up your work in MS Word using the equation editor and submit it using the Midterm Exam
Dropbox. You should make your submissions after you complete the exam.
A slide projector needs to create a 98-cm-high image of a 2.0 cm slide. The screen is 300 cm from the
slide. What focal length does the lens need? Assume that it is a thin lens. How far should you place the
lens from the slide?
We can draw the following ray diagram. Distance between slide and lens is x and distance between
srceen and lens is (300-x). Focal length = x.
49
300-x
1
X
Observe the similar right angle triangles formed. you have one triangle with one side (vertical) 1 cm,
and another side as x. The other triangle has one side as 49 cm and the other side as 300 - x.
using the law of similar triangles,
x/1 = (300-x)/49
49x = 300 - x
50x = 300
x=6
So focal length of the lens is 6 cm. the lens should be placed 6 centimeters from the slide.