What mass of steam at 100∘C must be added to 1.90 kg of ice at 0∘C to yield liquid water at 15 ∘C? The heat of fusion for water is 333 kJ/kg , the specific heat is 4186 J/kg⋅C∘ , the heat of vaporization is 2260 kJ/kg .

When a potential difference is applied to the piece of metal wire, a current of 4.1 mA flows through it. if this wire is replaced with a silver wire having twice the diameter of the original wire, how much current will flow through the silver wire?

Assume that the lengths of the potential difference across both wires are the same. ( the resistivity of the original metal is 1.68x10^-2 ohm . m, and the resistivity of silver is 1.6x10^-8 ohm . m )

Suppose that a particle with charge q and mass m is initially at the origin with zero velocity in the presence of external electric and magnetic fields given by

E = (Ex, 0, Ez),

B = (0, 0, Bz).

(1) Find x(t) and draw the trajectory the particle follows in space.

A pair of radio transmitters separated by 118m along a north-south line each transmit an in-phase 5.55MHz wave. Using small angle approximations, the smallest angle (with respect to the easterly direction from the pair of transmitters) of destructive interference is closest to

A.16°

B.19°

C.6.4°

D.9.7°

E.13°

A basketball is thrown vertically up from a 1.6‑m height with an initial speed v₀ = 23 m/s. At what speed will the ball hit the ground?

The speed of the ball, v₁ =  

How long will it take for the ball to reach the ground?

The time of flight, t₁ =  

Now the basketball is thrown vertically down from the same 1.6‑m height and with the same initial speed v₀ = 23 m/s. First, check your physical intuition and complete the following two statements:

If the initial velocity is directed down, the final speed of the ball (Select an answer: decreases, increases, stays the same, do not know) .

If the initial velocity is directed down, the time of the free fall (Select an answer: decreases, stays the same, increases, do not know) .

Now, with the new conditions, what will be the speed of the ball just before it hits the ground?

The speed of the ball, v₂ =  

How long will it take for the ball to reach the ground?

The time of flight, t₂ =  

Four lawn sprinkler heads are fed by a 1.7 cm diameter pipe. The water comes out of the heads at an angle of 40 ∘ to the horizontal and covers a radius of 7.8 m .

A) What is the velocity of the water coming out of each sprinkler head? (Assume zero air resistance.)

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

B) If the output diameter of each head is 2.8 mm , how many liters of water do the four heads deliver per second?

Express your answer using two significant figures.

C) How fast is the water flowing inside the 1.7 cm diameter pipe?

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

You put a can of water into a fire. The can heats up, and the water remains liquid. Neglecting the tiny change in volume due to thermal expansion, the change in the internal energy of the water is __________the heat absorbed by the water.

Two harmonic waves of pulsation m and amplitude a overlap at a point P. It is observed that also the resulting wave has amplitude equal to a.
> Calculate the phase shift Δφ between the two waves;
> Calculate the phase shift of the resulting wave with respect to the original wave it has
minor initial phase. If the phase shift of the two harmonics is 180 °, how much the resulting wave amplitude would become?
data:
1. amplitude of the waves: α
2. phase displacement Δφ = 180 °
Unknows:to calculate
1. phase displacement Δφ = ?
2. Initial phase of the resulting wave: Φο =?
3. Amplitude of the resulting wave A =?

A police siren of frequency is attached to a vibrating platform. The platform and siren oscillate up and down in simple harmonic motion with amplitude and frequency . (a) Find the maximum and minimum sound frequencies that you would hear at a position directly above the siren. (b) At what point in the motion of the platform is the maximum frequency heard? The minimum frequency? Explain.

Can you explain part B in details?thank you

Question 2: In a steam power plant operating according to the ideal intermediate superheated Rankine cycle, water vapor enters the high pressure turbine at 8 MPa pressure and 500 ^oC temperature and expands to 3 MPa pressure. Then, the steam is re-heated to a temperature of 500 ^oC in the boiler and expands to 20 kPa condenser pressure in the low pressure turbine.

I. Show the cycle in the T-s diagram and explain for what purpose intermediate superheating is done.

II. Calculate the total turbine work.

III. Calculate the thermal efficiency of the cycle.

(a) What is quantum tunneling?

(b) Based on the concept of quantum tunneling, describe the working principle of a scanning tunneling microscope.

(c) Explain what is quantum confinement?

(d) You have a metallic nanowire. The length of the nanowire is 1 mm (Comparing with the wave length of electrons, you can think the length is infinitely long.) The width of the nanowire is 50 nm. The height of the nanowire is 20 nm. Based on the simple model we discussed in our lecture, write out the formula of the energy of electrons in the nanowire (formula is enough, no calculation is required).

Cut the copper cubes to a volume of 0.5 cm^3. If the copper has a density of 8.96 g / cm^3
1 If 1 copper atom has 1 Conduction electron, calculate the total number of Conduction electrons in the copper cube.
2 At room temperature, the conduction electrons in the copper cube behave as Ideal gas or Degenerate gas. Why?
3 Explain the meaning of Fermi energy and Fermi temperature.
4 At zero Kelvin temperature, what energy can the Conduction electrons in the copper cube be? And find the total power of the Conduction electrons
5 How are Conduction electrons different from item 3.4?

If the net force on an object is zero then
Group of answer choices

the object's speed can change.

the object must be at rest.

the object's speed is constant but its direction might be changing.

the object has zero acceleration.