Related to Astrophysics

Explain what is the Gamow peak

Explain why a fast neutron (1-10MeV) has a much higher relative biological effectiveness (RBE) than a positron that results from a beta decay.

4) A nucleus of radioactive radium (226Ra), initially at rest, decays into a radon nucleus (222Rn) and an alpha-particle (a 4He nucleus). If the kinetic energy of the alpha-particle is 6.72 × 10^ -13 J, what is (a) the recoil speed of the radon nucleus, and (b) its kinetic energy? The superscripts indicate, roughly, the mass of each nucleus in unified mass units (u), where 1 u = 1.66 × 10^ -27 kg.

WILL RATE YOU!!!

Suppose you wanted to hang a frame imaged on the wall. The object will be hanging by two strings. Both of the strings attached are at the top of the framed imaged. The second string angel is 142 degrees (counter-clockwise from right) and the first string angel is 52 degrees (counterclockwise from right) and the tension is 48 N.

-Make a force diagram. What could be the tension in the second string?

-What must be the mass of the object hanging?

1. The U.S. Navy has long proposed the construction of extremely low-frequency (ELF waves) communications systems; such waves could penetrate the oceans to reach distant submarines.

Calculate the length of a quarter-wavelength antenna for a transmitter generating ELF waves of frequency 91 Hz.
km =

2. What are the wavelength ranges for the following?

(a) the AM radio band (540-1600 kHz)
m (maximum wavelength)
m (minimum wavelength)

(b) the the FM radio band (88-108 MHz)
m (maximum wavelength)
m (minimum wavelength)

3. The angle of incidence of a light beam in air onto a reflecting surface is continuously variable. The reflected ray is found to be completely polarized when the angle of incidence is 57.0

Calculate the energy of the lowest allowed energy level (the ground state) according to Bohr's Model of the Hydrogen Atom. Give your answer in units of eV with two decimals.

Which property affects the strength of a rope?

I have a practical for physics lab soon. Can you walk me through how to do the following and the equations I would need.

Measure the combined focal lengths of a two-lens combination consisting of a spherical and cylindrical lens in contact. Qualitatively compare measured and expected values.

Apparatus: An optical track with two lenses (spherical and cylindrical); a ruler; and a lamp-house with a coarse wire mesh on it. The focal length of each lens will be given to you.

Procedure:

Put the spherical lens and the cylindrical lens together on

the track as close as they can go. Put the screen on the track, at the op-

posite end from the lamp-house. Move the two-lens combination until an

appropriately sharp real image is formed. It may also be necessary to make

adjustments by rotating the cylindrical lens in its holder. Measure object

distance and image distance. Next move the screen closer to the two-lens

combination until a second appropriately sharp real image is formed. Again,

measure object distance and image distance. From the object and image

distances, calculate the focal length corresponding to each image. Then, us-

ing the focal lengths of each individual lens as given to you, calculate the

expected focal lengths of the two-lens combination. Qualitatively compare

these expected focal lengths to the ones calculated from image and object

distances.

1. A particle mass 10x10^-25 kg and charge +3x10^-16 C is projected with a velocity of 5x10⁶ m/s in the +x-direction into a uniform magnetic field of 2.0T in the -z direction. Whic of the following is correct?

a.) The particle will follow counterclockwise circular path of radius 0.833 mm

b.) none of the choices

c.) The particle will follow clockwise circular path of radius 0.833 mm

d.) The particle will follow an upward path (+y direction) of radius 8.33 mm

e.) The particle will follow an downward path (+y direction) of radius 8.33 mm

2. Which of the following is NOT true for principal rays passing through a converging lens?

a.) Incident rays passing through the optical center of the lens does not deviate from its original path.

b.) Incident rays from an object at infinity and parallel to the principal axis are refracted to the focus on the same side of the lens.

c.) All of the choices are true.

d.) Incident rays passing through the focus before the lens are refracted parallel to the principal axis.

e.) Incident rays parallel to the principal axis are refracted to the focus on the other side of the lens.

Use the inverse square law to estimate how the brightness of the Sun would change if you moved from Earth at 1 AU to Saturn's location at 10 AU (i.e., give a fraction or percentage, not magnitude). Then, the brightest known star is R136a1 with an absolute magnitude of -12.5, explain why you cannot make a precise determination of its brightness as seen from Earth without more information

A material particle with mass M moves under the gravitational effect of the earth. Solve the Hamilton-jacobi equation of the particle.

1. A 10-volt voltage source is connected in a series arrangement with two resistors (R1 = 7 ohms, R2 = 3 ohms). The current flowing in each resistor is:

a) 1.8 amperes   b) 45 amperes   c) 0.05 amperes   d) 1 ampere    e) 3.5 amperes

2. What is the voltage across R2 in the above circuit?

a) 2 volts   b) 10 volts   c) 3 volts   d)   0.25 volts   e)   5 volts

       3. If R1 and R2 are now connected in parallel, what is their effective resistance?

a) 2.1 ohms    b) 10 ohms   c) 14.8 ohms   d) 0.04 ohms    e) 4 ohms

. A 10 volt battery is connected to a RC DISCHARGE circuit made up of an unknown capacitor that is connected in parallel with a 1,000 ohm resistor. If the half life of this circuit is 10 seconds, what is the value of the unknown capacitor?

a) 0.0144 F   b) 12.28 F    c)   16.2 F   d)   0.025 F   e) 693 F

5. How long will it take this circuit to discharge from 10 volts to 1.25 volts?

a)   22 s    b) 69 s    c)   100 s    d) 30 s    e) 125 s

6. A wire carrying 10 amperes of current is oriented at 90 degrees with respect to a magnetic field of 5 Tesla. How long must the wire be to generate a force of 5 Newtons?

a) 0.1 meters   b) 15 meters   c) 2 meters   d) 7.07 meters    d) 0.005 meters

Your friend has decided to make some money during the next State Fair by inventing a game of skill. In the game, as she has developed it so far, the customer shoots a rifle at a 5.0 cm diameter target falling straight down. Anyone who hits the target in the center wins a stuffed animal. Each shot would cost 50 cents. The rifle would be mounted on a pivot 1.0 meter above the ground so that it can point in any direction at any angle. When shooting, the customer stands 100 meters from where the target would hit the ground if the bullet misses. At the instant that the bullet is fired (with a velocity of 1200 ft/sec according to the manual), the target is released from its holder 7.0 meters above the ground. (You see, the trigger is electronically connected to the release mechanism.) Your friend asks you to try out the game which she has set up on a farm outside of town. Before you fire the gun you calculate where you should aim. You may, as usual, neglect any effects of air resistance. Your conclusion? At what angle from the vertical should you aim?

Ceramics exhibit a greater range of electrical conductivity than any other class of materials. Explain why this is the case and provide some examples to illustrate this statement. Include discussion of the temperature dependence of conductivity for your examples.