Calculate the amount of energy required to escape from the surface of the following bodies, relative to that required to escape from the surface of Earth.

(a)    Uranus
                     energy to escape Earth

(b)    Mars
                             energy to escape Earth

Explain how a p - n junction works like a solar cell.

Please Summarize the follwing article (this is for a presentation)

"When you release a yo-yo, gravity acts on its center of mass to pull the yo-yo downward. Because the string of the yo-yo is wrapped around the yo-yo's axle, and because one end of the string is attached to your finger, the yo-yo is forced to rotate as it drops. If the yo-yo could not rotate, it would not drop.

Just as any object falling in a gravitational field, the rate of drop increases with time and so, necessarily, does the rotation rate of the yo-yo. The rate of drop and the rotation rate are greatest when the bottom is reached and the string is completely unwound. The spinning yo-yo contains angular momentum (or rotational kinetic energy) derived from the gravitataion potential energy through which the yo-yo has dropped.

Usually, the string is tied loosely around the axle so that the yo-yo can continue to spin at the bottom. Because the full length of the string has been paid out, the yo-yo can drop no further and, consequently, the rotation rate cannot increase further. If left in this condition, the friction between the axle and the string will eventually dissipate the energy of rotation or, equivalently, the angular momentum of the yo-yo and the yo-yo will come to rest.

However, a momentary tug on the string causes the friction between the string and the axle briefly to increase so that the axle no longer slips within the string. When the axle thus stops slipping, the angular momentum of the spinning yo-yo is sufficient to cause the string to wind around the axle. This, of necessity, causes the yo-yo to begin to 'climb' back up the string. After the first one or two rotations, the string can no longer slip, so the process of climbing up the string continues beyond the momentary application of the tug.

As the yo-yo continues to climb back up the string, the angular momentum (or kinetic energy of rotation) of the yo-yo is converted back into gravitational potential corresponding to the increasing height of the center of mass of the yo-yo. For this reason, the yo-yo's angular momentum and, hence, its rotation rate, steadily decreases as the yo-yo rises. This is, of course, the reverse of the process when the yo-yo was dropped.

If not for frictional losses, the yo-yo would climb all the way back up the string to your hand just as its rotational rate decreases to zero. But, due to friction, the yo-yo does not in fact quite get back up to your hand before it stops rotating.

Thereafter, the process repeats, with the yo-yo returning short of its previous height on each cycle. Eventually, the yo-yo comes to rest at the bottom.

Of course, as everyone knows, it is possible to keep the yo-yo going indefinitely by giving it a slight upward pull on each cycle. This pull can be combined with the tug required to initiate the climb back up the string. The pull serves to give the center of mass of the yo-yo a little extra kinetic energy to compensate for frictional losses, so that the yo-yo can be kept going indefinitely.

Yo-yos can also be thrown horizontally, or launched in other directions. The principle of operation is then just the same except that the kinetic energy of the center of mass, which is converted into spin as the string unwinds, results from being thrown, rather than from falling through a gravitational potential."

As an airplane is taking off at an airport its position is closely monitored by radar. The following three positions are measured with their corresponding times:
x₁ = 264.08 m at t₁ = 4.90 s,
x₂ = 312.33 m at t₂ = 5.40 s,
x₃ = 364.72 m at t₃ = 5.90 s.
What is the acceleration of the airplane at t₂ = 5.40 s? (Assume that the acceleration of the airplane is constant.)​

a=_______m/s^2

Two radio antennas are 140 m apart on a north-south line. The two antennas radiate in phase at a frequency of 5.2 MHz. All radio measurements are made far from the antennas. The smallest angle, reckoned east of north from the antennas, at which constructive interference of two radio waves occurs, is closest to:

28

Find three applications of quantum tunneling used in electronics and explain the principles in detail.

28) What process(es) cause the gaps in the rings of Saturn?

Problem (M-33). You are given a crystal of strontium at room temperture, or 300K. Draw the crystal structure and find the number density of conduction electrons in the classical picture. Is this a non-metal?

The frequency of light reaching Earth from a particular galaxy is 16% lower than the frequency the light had when it was emitted.

A thin 0.100-kg rod that is 350mm long has a small hole drilled through it 87.5mm from one end. A metal wire is strung through the hole, and the rod is free to rotate about the wire.

Part A

Determine the rod's rotational inertia I about this axis.

Express your answer with the appropriate units.

I = ?

Part B

Determine the period of the rod's oscillation.

Express your answer to two significant digits and include the appropriate units.

T = ?

whats the advantage of the extended media surface area in pleated filters?..a filter can be flipped over when one side is dirty...b. can be folded..c. creates cyclonic filtration action between the pleats..d. provides much greater dust-holding ability

At rest, a car's horn sounds the note A (440 Hz). The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 403 Hz.

(a) Is the cyclist ahead of or behind the car?

ahead/behind    

(b) What is the speed of the car?
(Answer in m/s)

The mattress of a water bed has a length of 2.00 m, a width of 2.00 m and a depth of 30.0 cm. Find the weight of the water on the mattress and find the pressure exerted by the water on the floor when the bed is in its normal position. Assume that the entire lower part of the bed makes contact with the floor.

1.If the bed were replaced by another that has a weight of 300 lbs and is supported by the four legs that have a diameter of 2.00 cm. What pressure does the bed exert on the surface?

a.5.00 x 105 Pa
b.4.5 x 105 Pa
c.6.0 x 104 Pa
d.2.7 x 105 Pa

2.The fluid presented in the exercise is a fluid:

a.Turbulent
b.Laminate
c.Incompressible
d.Viscous

A person's lower leg is 1 meter long and has a mass of 9.5kg. It is allowed to swing freely. If the leg is treated as a simple pendulum with a length equal to the length of the leg, using T = 2pi square root of L/g root of 2/3

Then, estimate the typical human walking speed based on your result, making clear any assumptions/estimates you make.