There is a line of negative charge (-Q) along the y axis (from 0 to L). There is a line of positive charge (+Q) along the x-axis (from 0 to L).

A) Find the electric field at the point (L/2, L/2). Sketch the direction of the field at this point on a diagram of the situation.

B) Find the potential at the point (L/2, L/2).

High-altitude mountain climbers do not eat snow, but always melt it first with a stove. To see why, calculate the energy absorbed from a climber's body under the following conditions. The specific heat of ice is 2100 J/kg⋅C∘, the latent heat of fusion is 333 kJ/kg, the specific heat of water is 4186 J/kg⋅C∘.

Part A: Calculate the energy absorbed from a climber's body if he eats 0.50 kg of -15∘C snow which his body warms to body temperature of 37∘C. Express your answer to two significant figures and include the appropriate units.

Part B: Calculate the energy absorbed from a climber's body if he melts 0.50 kg of -15∘C snow using a stove and drink the resulting 0.50 kg of water at 2∘C, which his body has to warm to 37∘C. Express your answer to two significant figures and include the appropriate units.

A simple insulator has a band gap of 4.0 eV, and the Fermi energy may be taken to reside in the middle of the gap. Estimate the probability of an electron at room temperature being in the conduction band.

Question B5

(a) A very hot 0.8 kg copper cylinder at temperature 365.84℃ is dropped into a 0.2 kg copper bowl contains 0.3 kg of water at 20℃. The final temperature of the system is 85℃. Given that specific heat of copper 386 J/kg·K and specific heat of water 4190 J/kg·K.

(i) Find the entropy change ∆S1 of the copper bowl and water.

(ii) Find the entropy change ∆S2 of the copper cylinder.

(iii) Find the net entropy change ∆Snet of the system. Is the process reversible or irreversible?

(b) What are the four processes of Carnot cycle?

A simple pendulum has a mass of 0.650 kg and a length of 7.00 m. It is displaced through an angle of 14.0° and then released. Using the analysis model of a particle in simple harmonic motion, calculate the following. (Give your answer to the thousandths place.)

(a) What is the maximum speed of the bob?


(b) What is the maximum angular acceleration of the bob? (rad/s²)

(c) What is the maximum restoring force of the bob?


(d) Solve parts (a)through (c) by using other analysis models. (Hint: you may need to use separate analysis models for each part.)

(e) Compare the answers.

A circuit consists of a large electromagnet that has an inductance of 52.0 H and a resistance of 8.00 ?, a dc 270 V power source, and an open switch - all connected in series.

A) How long after the switch is closed is the current equal to 10.5 A?

B) How long after the switch is closed is the current equal to 31.9 A?

Meteoroids, meteors, and meteorites are all related. Choose the correct time-ordered pairing.

What are the three types of meteorites?

What is the least common type of meteorite?

Which type of meteorite has the Widmanstatten pattern?

A car with mass 1309 kg is travelling north at a speed of 28.9 m/s. It collides at right angles with a truck (m=2733 kg) travelling east at 16.6 m/s and the two vehicles stick together after the collision. How much kinetic energy is lost during the collision?

• If a block of mass m at speed v collides inelastically with a block of mass M at rest, what is the final velocity of each block? What fraction of the initial energy is lost?

• Two identical circular hockey pucks of radius r traveling towards each other at the same speed v collide elastically. Their centers are separated by a vertical distance d, which is less than r. After the collision, with what angle relative to the initial path of the pucks will each one travel along?

• Explain the physics of Newton’s Cradle.

1. Derive Laws of Black Body Radiation from Wien’s Law: u_ν = ν³F(ν/T)
   1. What is Stephen’s Law?
   2. Please Prove Stephen’s Law from Wien’s Law
   3. Please Prove Wien’s Displacement Law from Wien’s Law

19 - 3 -4

A heat engine operates between a reservoir at 29°C and one at 341°C.

What is the maximum efficiency possible for this engine?

heat engine operates in a Carnot cycle between 88.0°C and 345°C. It absorbs 21,200 J of energy per cycle from the hot reservoir. The duration of each cycle is 3.00 s.

(a) What is the mechanical power output of this engine?
kW

(b) How much energy does it expel in each cycle by heat?

The sound from a busy highway contains a 500 Hz Fourier component whose power at the highway is 1.5 ✕ 10⁻⁶ watt/m. (Ignore sound interactions with the ground).

(a)What are the sound intensity (in W/m²), the sound intensity level (in dB) and the loudness (in phon) of that Fourier component at a distance of 25 m from the highway?

intensity=?  W/m²

intensity level =? dB

loudness=?  phon

(b)What are the sound intensity (in W/m²), the sound intensity level (in dB) and the loudness (in phon) of that Fourier component at a distance of 50 m from the highway?

intensity=? W/m²

intensity level=? dB

loudness=? phon

A package of mass 50 kg sits on an airless asteroid of mass 1.25 x 10^13 kg and radius 1000 m. We want to launch the package straight up so that it reaches a maximum distance of 4000 m from the center of the asteroid, where it will be picked up by a waiting ship before it can fall back down. We have a powerful spring whose stiffness is 1000 N/m. How much must we compress the spring to release it with the energy needed to reach the required altitude?

A 8.50 kg mass is attached to the end of a hanging spring and stretches it 28.0 cm. It is then pulled down an additional 12.0 cm and then let go. What is the maximum acceleration of the mass? At what position does this occur? What is the position and velocity of the mass 0.63 s after release?