A long straight wire lies on a horizontal table and carries an ever-increasing current toward the north. Two coils of wire lie flat on the table, on on either side of the wire. When viewed from above, the direction of the induced current is

How does the OLED produce light? (illustrate answer with energy level diagram)

A turntable of 0.8 m in diameter is spinning about its axis with an initial angular velocity of 4 rad/s. If it experiences a constant angular acceleration of 3 rad/s 2 , find: A) The angle through which the turntable has travelled from 0 sec to 2 sec. B) The arc length the turntable’s rim has travelled from 0 sec to 2 sec. C) The tangential speed of the turntable’s rim at t=2 sec. D) The tangential acceleration of the turntable’s rim at t=2sec. E) The radial acceleration of the turntable’s rim at t=2sec

A capacitor filled by dielectric slab (k=4.5) is connected to a 12.0V battery and charged up. The capacitor is then disconnected from the battery and the slab is removed.

a) Find the amount by which the potential difference across the plates changes.

b) Find the difference between the new stored energy and the original amount and specify whether this energy difference is an increase or decrease.

A rail gun uses electromagnetic forces to accelerate a projectile to very high velocities. The basic mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 40.0 g and electrical resistance 0.200 Ωrests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 10.0 cm apart. (Figure 1) The rails are also connected to a voltage source providing a voltage of V = 5.00 V .
The rod is placed in a vertical magnetic field. The rod begins to slide when the field reaches the value B = 7.84×10⁻² T . Assume that the rod has a slightly flattened bottom so that it slides instead of rolling. Use 9.80 m/s2 for the magnitude of the acceleration due to gravity.

Find μs, the coefficient of static friction between the rod and the rails.

Consider two point charges located on the x axis: one charge, q1= -19.0 nC , is located at x1 = -1.700 m; the second charge, q2 q= 40.0 nC , is at the origin (x = 0).

What is (F_net3)x the x-component of the net force exerted by these two charges on a third charge q3 = 54.5 nC placed between q₁ and q₂ at x₃= -1.160 m ?

Your answer may be positive or negative, depending on the direction of the force.

To get to a concert in time, a harpsichordist has to drive 122 miles in 1.93 hours. (a) If he drove at an average speed of 52.0 mi/h in a due west direction for the first 1.22 h, what must be his average speed if he is heading 30.0° south of west for the remaining 42.6 min?(b) What is his average velocity for the entire trip?(give magnitude and direction)

A thin-walled hollow cylinder with mass m₁ and radius R₁ rolls without slipping on the inner wall of a larger thin-walled hollow cylinder with mass m₂ and radius R₂ >> R₁. Both cylinders' axes are aligned and horizontal, and some magical mechanism ensures this perfect friction contact between them. Unfortunately for you, the larger cylinder rolls without slipping on a horizontal surface. Describe the motion including small oscillation frequencies near any equilibria if the systems is released from rest with the inner cylinder at some angle α₀.

Radioactive iodine is given to patients to reduce thyroid growth or activity. The iodine I₅₃¹³¹, has a half-life of 8.04 days. Why would the radiation in the human body decrease at a faster rate than at the calculated rate?

A nail contains trillions of electrons. Given that electrons repel from each other, why do they not fly out of the nail?

Nuclear fission reactors consist of three main components: the fuel rods, control rods and the moderator. Draw a diagram of typical reactor and give a brief description of each of the main components. Why are fusion reactors considered ‘cleaner’ than fission reactors?

2. A 10 kg ball moving to the right with a speed of 6.0 m/s collides with a 20 kg ball moving to the left at a speed of 4.0 m/s.

(a) If this is a head-on, perfectly inelastic collision, what is the velocity of the balls after the collision. Give magnitude and direction. (5 pts.)

(b) If this is a head-on collision and the the 10 kg ball moves to the left with a speed of 7.0 m/s after the
collision, what is the velocity of the 20 kg ball after the collision? Give magnitude and direction.

(c) Is the collision in part b perfectly elastic? (You must show a calculation here.) (5 pts.)

(d) If the balls are in contact for 0.03 seconds during the collision in part (b), what is the magnitude of
the average force that each ball exerts on the other? (5 pts.)

(e) Write an equation for conservation of momentum in the x direction and determine the x component of the
velocity of the 20 kg mass. (5 pts.)

(f) Write an equation for conservation of momentum in the y direction and determine the y component of the

velocity of the 20 kg mass. (5 pts.)

A plane of area 0.25m2and surface charge density s=4.5 nC/m2 lies in the x = 0.00 m plane, and a second plane of surface charge density s= -4.50 nC/m2 lies in the x = 0.0200 m plane. Find:a.find the capacitance, the stored charge, and the potential energy of the system. b.the electric potential difference between the 2 planes.c.the electric field at (i) x = 0.0180 m and (ii) x = 0.0500 m (508 N/C and 0 N/C). d.What is the maximum charge that this capacitor can hold before it breaks down? e. A charged particle of mass 6.64x10-27kg travels the distance two charged plates in 2.84x 10-7s. Find the charge of the particle.

*Please don't forget to answer part E. Thank you!

A block of mass m = 2.6kg is attached to a single spring of spring constant k = 4.4Nmand allowed to oscillate on a horizontal, frictionless surface while restricted to move in the x-direction. The equilibrium position of the block is x=0m. At time t=0s the mass is at position x=2.7m and moving with x-component of velocity vx=−6.8ms. What is the x-component of velocity at time t=1.3s? Answer in meters per second.