A small meteorite (30 kg) is falling through the earth’s atmosphere. It is moving very fast - in fact, faster than the terminal velocity it would have reached if had been dropped from a great height. In a situation like this, the drag force is stronger than the weight. At one moment, the magnitude of the meteorite’s acceleration is 4.0 m/s². You need to calculate the magnitude of the drag force on the meteorite.

1. Draw a free-body diagram, which includes an arrow for each individual force on      the meteorite (and labels to indicate the type of force), an arrow for the net force,      and a coordinate system.     

2. In this situation, the velocity of the meteorite and the acceleration of the meteorite point in [the same direction, in opposite directions].

3. In this situation, the velocity of the meteorite and the net force on the meteorite      point in [the same direction, in opposite directions].

4. In this situation, the magnitude of the drag force on the meteorite is [increasing,      decreasing, remailing constant].

5. Write an algebraic expression that shows how the individual forces combine to      produce the net force on the meteorite. The signs in the expression must be

              consistent with the coordinate system in the free-body diagram. (That is, add in      all the forces in the positive direction and subtract all the forces in the negative      direction.)

6. Set that expression equal to ma and solve the resulting equation for the

              magnitude of the drag force. Type out the equation with all known numbers      inserted in their proper places and then just state the answer.

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A cannonball is fired at a cliff 1000 m away and strikes it 250 m above the level ground 5 seconds later.

a. What is the angle (in degrees) with which the cannonball was fired, with respect to the level ground? (g = 10 m/s²)

b. What was the approximate initial speed (in m/s) with which the cannonball was fired? (g = 10 m/s²)

c. Which time (in seconds) below is the closest to the time after firing that the cannonball reaches (or would reach) maximum height? (g = 10 m/s²)

Big Ben in London is the most accurate mechanical clock of its size. The 300-kg hour hand is 2.7 m long, and the 100-kg minute hand is 4.2 m long. Treat each hand as if it were a thin rod. Calculate the rotational kinetic energy of the two-hand system.

Derive the Jones matrix of a liquid crystal cell?

Why can gravitational potential energy be ignored in a verticle spring with a hanging mass? My TA mentioned something about no work being done by GPE, but that doesn't really make sense. Also, the assignment is asking for it to be explained conceptually, not with equations. Thanks!

A 65.0 kg man is riding on a 12.5 kg bicycle. Together they have a kinetic energy of 2.80 x 10^3. If the bicycle has wheels with radii of 0.450 m, then their frequency of rotation is

Calculation of half-life for alpha emission using time-independent
Schrodinger Equation using the following following information:
Radionuclide: 241-Am (Z=95); Ea = 5.49 MeV; Measured Half-Life~432y

Follow the steps involved and show your work for each subset question, not the
final answer:
(a) Evaluate the well radius [=separation distance (r) between the center of
the alpha particle as it abuts the recoil nucleus];
(b) Evaluate the coulomb barrier potential energy (U) for the well;
(c) Estimate the separation distance (r*) from the center of the potential well
where the coulomb potential equals the energy of the alpha particle;
(d) Assuming a square shaped single barrier of height “U”, evaluate the
tunneling probability by solving for the transmission coefficient and use of
the associated separation (=r*-r);
(e) Calculate the frequency with which the alpha particle strikes the well
boundary to try to get out of the well;
(f) Calculate the half-life and compare it with the known half-life for alpha
emission from 238U;
(g) Use the spatially-averaged effective approximation for the height of the
barrier by integrating the variation of “U” with distance from “r” to “r*” and
re-calculate the half-life and compare it with the known half-life for alpha
emission from 238U;
(h) Approximate the hyperbolic shaped barrier variation outside of the well
by breaking them up into 5 progressively reduced height square shaped
barriers, each with a width = (r*-r)/5 and calculate the tunneling
probabilities associated with each segment;
(i) Re-calculate for the half-life combining the probabilities from each of the 5
bins, and compare the value with the known half-life.

What must be the position of an object in order that it may be seen distinctly through a +9.0 D lens placed 2.9 cm in front of an eye, the eye being accommodated for a distance of 35.5 cm? Give your answer in cm as a distance to the lens.

Marc drives like a maniac. His defense is always "It’s OK, I know the physics of driving so I do it safely". Marc is coming up to a horizontal turn of radius r = 150 m. Since Marc is a physicist, he just knows the coefficient of static friction between the tires and the road is µ = 0.45. If the center of mass of Marc’s car is xcm = 60 cm above the ground and his car’s wheel base is ` = 1.3 m, determine the following:

(a) a formula for the maximum speed Marc can complete the turn without flipping the car.

(b) a formula for the maximum speed Marc can complete the turn while remaining on the road (hint, you will have to compare the value from two formulas).

(c) whether Marc can safely complete the turn if his speed is 100 km/h? What about at 80 km/h?

(d) Show that if µs < ` 2xcm , then it is impossible to flip your vehicle.

(e) The above ratio is something that vehicle engineers must be aware of (as it is a safety thing). Moving vans, obviously, have a much higher center of gravity, however, due to width constraints (width of lanes on the road, parking spots, etc), they are not able to make the wheelbase that much wider. If the wheelbase of a moving van is 2 m and it’s center of mass (when modestly loaded) is 5 ft, is it able to flip (using the same µs as above)?

The weight of an astronaut on Earth surface is 950 N. What is the astronaut weight in a satellite orbiting Earth at an altitude of 500km with a speed of 450 m/s? (g=9.8 m/s2 and REarth = 6400 km). Select one: a. 790 N b. 815 N c. 852 N d. 1020 N

1. Discuss any ethical or practical considerations that might arise from application of Ultraviolet light.

2. How different wavelengths of the electromagnetic spectrum are applied in real life. These might include (but are not limited to) environmental impact, safety concerns, or issues of effectiveness.

Your summary must be in your own words.

Explain both Newton’s and Einstein’s views of gravity between earth and the moon. Make sure your answer is detailed and specific.

The closest distance a book can be read from a pair of reading eyeglasses (Power = 2.06 dp) is 27.5 cm. What is the near distance? (Assume a distance between the eyeglasses and the eyes to be 3.00 cm)

1. If I=35,000 time the threshold of hearing, what is the difference in db?

2. Mathematically prove that the threshold of pain is 130db. (Mathematically prove means to show an equation and solution)

3. If one speaker is quieter than another, what is the reduction in db?

a. If it has only 1/3 the intensity of the other?

b. If it has only 1/6 the intensity of the other?

4. Mathematically prove that a 10db increase is 10 times the power, and only 3.16 times the pressure/voltage. (Show an equation and solution)

5. Describe the difference between A weighting and C weighting (be thorough but concise).