The largest downward force you can exert on a certain multiple pulley system = 777 N. When you move the rope 3.5 m, the object moves 0.35 m. What is the heaviest object you could lift? Could it lift a cow that's 1600 lbs?

A mass weighing 4 pounds stretches a spring 4/3 ft. The entire system is immersed in a fluid offering a damping force numerically equal to the instantaneous velocity. Beginning at t=0, an external force equal to f(t)=e^-t is impressed on the system. Determine an initial valued differential equation for the displacement of the mass from its equilibrium point at time t>0.

10.How does a light-emitting diode work? Why are there different colors of LEDs?

Find an article about recent findings in physics from a reputable source. After you've read your article, Summarize it in 1-2 paragraphs. In an additional paragraph, discuss any evidence presented in the article. Use the following questions to help guide you: What, if anything, does this evidence support? Is it relevant to the author's main idea(s)? Is a claim made or a position taken on a scientific issue? If so, to what degree does the evidence and reasoning in the text support that claim? Cite your source.

Please answer question 2b. If you are writing by hand please make handwriting as readable as possible.

2. Lithography:
(a) Polymers containing aromatic rings are more likely to absorb UV photons, leading to chain scission. Would this make them negative or positive resists for lithography. (2 points)

(b) Explain briefly how lift off works. (2 points)

(c) Explain why chips are exposed with a stepper (so only a small field of view is illuminated at a time) in deep UV lithography? (2 points)

(d) Looking at the electron trajectories in Fig 5.8.explain why it would be useful to have a resist with a fairly sharp threshold exposure needed to make it soluble. (2 points)

(e) It is desired to etch away the whole thickness of a silicon wafer with a well- defined etch angle. How can this be achieved? ( 2 points)

Copernicus's heliocentric model and Ptolemy's geocentric model were each developed to provide a description of the solar system. Both models had advantages that made each an acceptable explanation for motions in the solar system during their time.

Sort each statement according to whether it is an advantage of the heliocentric model, the geocentric model, or both.

Drag the appropriate items to their respective bins.

• Planetary orbits and motions based on Greek ideologies of perfect form and motion
• Predicted planetary positions accurately over relatively short time periods
• Explained planetary motions and brightness changes most simply
• Rooted in widely accepted religious beliefs regarding Earth's place in the universe

• Heliocentric:

• Geocentric:

• Both geocentric and heliocentric:

In a downhill ski race surprisingly little advantage is gained by getting a running start. This is because the initial kinetic energy is small compared with the gain in gravitational potential energy even on small hills. To demonstrate this, find the final speed and the time taken for a skier who skies 75.0 m along a 30° slope neglecting friction for the following two cases. (Note that this time difference can be very significant in competitive events so it is still worthwhile to get a running start.)

(a) starting from rest final speed ._______ m/s

time taken__________ s

(b) starting with an initial speed of 2.00 m/s

final speed__________ m/s

time taken__________ s

An object is attached to the bottom of a glass plate with index of refraction 1.5. Three light rays (a, b, c) emanating from the object are shown; they make angles of 0o (a), 30o (b), and 60o (c) with the normal. An air-filled gap separates the glass plate from the front lens of an optical instrument that is used to view the object. The lens is also made of glass with index of refraction 1.5 We are interested in the paths of the rays from the object into the front lens (how they leave is not our concern).

a)

When is total internal reflection at a glass/air interface possible?

Question 17 options:

b)

What happens to ray a as it passes from the glass plate through the gap into the front lens?

Question 18 options:

c)

Write an equation for the angle that ray b makes with the normal to the glass-air interface inside the gap. Then calculate the value in degrees.

d)

For ray b, what is the angle with the normal inside the front lens?

Question 20 options:

e)

What is going to happen to ray c? Give a brief description of its path.

f)

Now assume that the gap is filled with oil with a matching index of refraction, 1.5.

(a) What will happen to the rays now?

(b) What does this imply for the brightness of the object's image when viewed through the instrument?

A four-turn circular wire coil of radius 0.550 m lies in a plane perpendicular to a uniform magnetic field of magnitude 0.355 T. If the wire is reshaped from a four-turn circle to a two-turn circle in 0.128 s (while remaining in the same plane), what is the average induced emf in the wire during this time?

Get a sheet of paper and draw a horizontal optical axis. Next, draw a vertical line near the center of the optical axis to represent your lens, then measure out and draw the focal points. Assume the focal length to be 2cm. Pick an object point 6cm away from the lens on the top left-hand side of the paper. Draw the three simple case rays – parallel, through the center of the lens, and through the focal point – and locate the image formed on the other side of the lens.

Question 1: Get another sheet of paper and repeat step 1, however instead draw the object point inside the focal length, 1cm away from the lens. Again draw the three simple case rays

What do you observe? Do the lines converge at a given point???

Question 2: Get a third sheet of paper and repeat the ray tracing procedure for a concave lens with focal length -2cm. Place the object outside of the focal length, 4cm to the left of the lens

Do the rays converge at a given point?

Explain graphically the differences in linear, circular, and elliptical polarization together with the quantities / formulas that represent each

Two identical point charges (q = +3.00 x 10-6 C) are fixed at opposite corners of a square whose sides have a length of 0.580 m. A test charge (q0 = -3.00 x 10-8 C), with a mass of 7.50 x 10-8 kg, is released from rest at one of the corners of the square. Determine the speed of the test charge when it reaches the center of the square.

A conventional activated-sludge plant treats 10.0 MGD of municipal wastewater with a BOD concentration of 240 mg/l and suspended solids of 200 mg/l. The sludge flow pattern is shown in Figure 11-1 of the textbook with a gravity belt thickener to concentrate the excess activated sludge. Primary and thickened activated sludge are pumped separately to the anaerobic digester. The primary clarifier removes 50% of the suspended solids and 35% of the BOD. The primary sludge solids content is 4.0%. The operating F/M ratio for the activated-sludge process is 0.3 lb BOD per day per pound of MLSS. The solids content of the waste sludge removed from the secondary clarifier is 16,000 mg/l; the gravity belt thickening captures 95% of the solids in the sludge and increases the solids content of the thickened sludge to 7%. Calculate: a) Flow rate of primary sludge, in gals/day b) Flow rate of thickened secondary sludge, gals/day. c) Flow rate and solids concentration of the blended sludge

Where do we experience centripetal force around us in real life. When would we use this concept "centripetal force" and "centripetal acceleration." I am trying to understand this concept and break it down in real life and in physics problem.