from my ATMO class

Suppose you are about to begin a rafting trip through the Grand Canyon. A guide unrolls your inflatable raft on the grass next to the river and pumps air into the raft until it becomes nice and firm. The raft is then placed onto the cold water of the Colorado River and is anchored to a tree by a rope. A short time later you notice that the raft has lost its firmness and has become “baggy”. A whiner in your group cries “Oh no! There is a hole in our raft. I’m not going!” But you say “Don’t worry the raft lost its firmness because it was put in the cold water.”  Use the kinetic model to explain why the raft would lose its firmness. In your answer you should relate the kinetic model explanation for the changes in the movement of gas molecules to what happens to the temperature and number density of the air in the raft after being placed in the cold water.

For a summer job you take a position as an accident investigator for your local police force. On your first day you are called to the scene of a possibly minor accident at a large intersection with a 4-way stop. From the positions of the cars you can see that driver A was traveling northward in a small car and driver B was traveling eastward in a car that looks like it has approximately twice the mass of car A. The debris from their collision is in the center of the intersection. You can see the 5 m long marks left by the skidding tires that lead from the impact point to where the cars now rest, stuck together. The skid marks point in a direction 18.4˚east of north. From your measurements of the marks and from knowing something about the frictional force of asphalt on tires, you estimate that the cars were moving about 20 miles per hour immediately after the collision. Driver A says that driver B ran through a stop sign. Driver B says the opposite. You determine the speeds that each driver was traveling to help determine who is at fault. Make sure that y explain clearly how you determined the speeds of each car.

Light of wavelength 600 nm passes though two slits separated by 0.25mm and is observed on a screen 1.1m behind the slits. The location of the central maximum is marked on the screen and labeled y = 0. A very thin piece of glass is then placed in one slit. Because light travels slower in glass than in air, the wave passing through the glass is delayed by 5.0

A simple pendulum consists of a particle of mass m suspended by a long, massless wire of length L. Draw a free body diagram for the pendulum bob corresponding to a moment when the bob is located an angular displacement Φ away from (eg. to the right of) equilibrium. Determine an expression in terms of m, g, and Φ for the component of the net force on the bob that points tangent to the path of the bob.

Assume that the pendulum bob undergoes small angular displacements from equilibrium, meaning sinΦ = tanΦ= Φ (radians). Simplify your expression for the tangential component of the net force and use Newton's Second Law to write down the resulting differential equation of motion for the angular position Φ(t) of the pendulum bob as a function of time. Explain how your differential equation of motion implies that the pendulum undergoes simple harmonic motion, and determine the frequency of motion in terms of the given parameters.

A particle of mass 9.794

5. A plastic rod of finite length carries a uniform linear charge Q = 10 μC along the x- axis, with the left edge of the rod at the origin (0, 0) and its right edge at (4, 0) m. All distances are measured in meters.

   1. (a) Determine the net electric field at a
      point P (10,0) m, along the positive x-axis.

   2. (b) Apply integral methods to find the x- and y-components of the electric field vector due to this charged rod at the point P2 (0, 3) m, along the y-axis.

   3. (c) If the right end of the uniformly-charged rod were extended to an infinite distance along the positive x-axis, determine the magnitude and direction of the net electric field at point P(0,3) m.

Problem 12.82

A 45kg figure skater is spinning on the toes of her skates at 1.1rev/s . Her arms are outstretched as far as they will go. In this orientation, the skater can be modeled as a cylindrical torso (40kg , 20 cm average diameter, 160 cm tall) plus two rod-like arms (2.5 kgeach, 71cm long) attached to the outside of the torso. The skater then raises her arms straight above her head, where she appears to be a 45 kg, 20-cm-diameter, 200-cm-tall cylinder.

Part A

What is her new rotation frequency, in revolutions per second?

A highway curve with a radius of 750 m is banked properly for a car traveling 120 km/h. If a 1600- kg Porshe 928S rounds the curve at 230 km/h, how much sideways force must the tires exert against the road if the car does not skid?

A block of mass m = 2.30 kg slides down a 30.0∘ incline which is 3.60 m high. At the bottom, it strikes a block of mass M = 6.20 kg which is at rest on a horizontal surface (Figure 1). (Assume a smooth transition at the bottom of the incline.) The collision is elastic, and friction can be ignored.

a) Determine the speed of the block with mass m = 2.30 kg after the collision.

b)Determine the speed of the block with mass M = 6.20 kg after the collision.

c)Determine how far back up the incline the smaller mass will go.

1. A rechargeable battery with emf 1.52 V and internal resistance 0.75 Ω is connected positive to positive and negative to negative with a 3.00 V battery with internal resistance 1.4 Ω. Assume the emf of each battery remains constant.

(a) Find the current.

(b) How much energy will be stored in the rechargeable battery in 1.00 minute?

(c) Determine the efficiency of this charging arrangement.

(d) How could the efficiency be improved (and wasted energy be reduced)?

1.

The intensity level of the sound reaching your ear from a speaker 25 m away is 110 dB.

(a) What is the intensity?

(Answer: 0.10 W/m2)

(b) If you move to a new distance of 7.9 m, what is the new sound intensity level in

decibels?

(Answer: 120 dB)

(c) What is the power output of the speaker?

(Answer: 784 W)

Research and summarize the concept of the Qauntum Computer and explain the concept of the Qubit as opposed to the traditional bit. Assess the viability of actually building one of these contraptions and identify some of the main physical/engineering barriers that exist to actually building one of these devices.

QUESTION 1:

Are electric force and electric field vector or scalar quantities?

QUESTION 2:

When an electron is placed in an electric field it experiences an electrostatic force towards the North.  In what direction is the electric field?

QUESTION

What is the magnitude of the electric field at a distance of 66 cm from a 76 μC charge, in units of N/C?

What are blackbody curves and what are the approximate shapes of such curves? What is the Stefan-Boltzmann law and how does it relate to a blackbody and a blackbody curve? What is Wien's displacement law and how does it relate to a blackbody and a blackbody curve?

A single mass m₁ = 3.5 kg hangs from a spring in a motionless elevator. The spring is extended x = 15 cm from its unstretched length. Spring constant is 228.9

2) What is the distance the lower spring is stretched from its equilibrium length?

3) Now the elevator is moving downward with a velocity of v = -2.7 m/s but accelerating upward with an acceleration of a = 5.5 m/s². (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

What is the force the bottom spring exerts on the bottom mass?

is the elevator speeding up? slowing down? moving at a constant speed?

6) Rank the distances the springs are extended from their unstretched lengths: