1. An ideal transformer has a primary with 25 turns and secondary with 15 turns. The load resistor is 24 ? and the source voltage is 85 Vrms.What is the rms electric potential across the 24 ? load resistor?

Answer in units of Vrms

2. A transformer consists of two coils of wire wound on a common toroidal iron core. The mutual inductance of the pair is 483 mH and the current in the first coil decreases from 29 A to 0 in 2.9 s.

What is the induced emf in the second coil? Answer in units of V.

3.If the outer coil has 14.7 turns, a radius of 19 cm and length of 7.47 cm and the inner coil has 628 turns, a radius of 7 cm, and a length of 33.3 cm, find the mutual inductance of the circular coil and solenoid.

Answer in units of ?H

4. Now the current in the solenoid is increased linearly at a rate of di/dt = a =20.2 A/s.

What is the magnitude of the voltage E across the circular coil?

Answer in units of ?V.

A 14.0 m uniform ladder weighing 480 N rests against a frictionless wall. The ladder makes a 63.0°-angle with the horizontal.

(a)

Find the horizontal and vertical forces (in N) the ground exerts on the base of the ladder when an 850-N firefighter has climbed 4.10 m along the ladder from the bottom.

horizontal force

magnitude Ndirection ---Select--- towards the wall away from the wall

vertical force

magnitude Ndirection ---Select--- up down

(b)

If the ladder is just on the verge of slipping when the firefighter is 9.20 m from the bottom, what is the coefficient of static friction between ladder and ground?

(c)

What If? If oil is spilled on the ground, causing the coefficient of static friction to drop to half the value found in part (b), what is the maximum distance (in m) the firefighter can climb along the ladder from the bottom before the ladder slips?

m

An electric motor exerts a constant torque of τ=10N⋅m on a grindstone mounted on its shaft; the moment of inertia of the grindstone is I=2.0kg⋅m2. If the system starts from rest, find the work done by the motor in 8.0 s and the kinetic energy at the end of this time. What was the average power delivered by the motor? Part A:Suppose we now turn off the motor and apply a brake to bring the grindstone from its greatest angular speed of 36 rad/s to a stop. If the brake generates a constant torque of 13 N⋅m , find the total work done (including signs) needed to stop the grindstone. Part A:Suppose we now turn off the motor and apply a brake to bring the grindstone from its greatest angular speed of 36 rad/s to a stop. If the brake generates a constant torque of 13 N⋅m , find the total work done (including signs) needed to stop the grindstone. Part B:Find the average power (including signs) needed to stop the grindstone in Part A.

Given is the rod of length L with the linear charge of density ?=?/? . The rod lies on the x axis with its midpoint at the origin. Find the electric field vector on y axis resulting from such continuous system of charge at distance y from the origin. Use this result to obtain the expression for electric field at distance y from the infinitely long wire.

1. In terms of edges, why is it an advantage to use mirrors over lenses in telescopes?

2. How does the placement of the eyepiece with Newtonian and Cassegrain reflectors differ?

3. What does the diffraction limit of a telescope depend upon?

Imagine that you have placed a compass due east of of a wire where current equals 2A (the wire is vertical and current travels from bottom to top).

1. If you turn the current on, how would the compass respond? (Does it change cardinal direction?)

2. How does the magnitude and direction of the total magnetic field change?

PLEASE EXPLAIN!

A neutron star has a mass of 3.35 × 1030 kg (about the mass of our sun) and a radius of 6.09 × 103 m. Suppose an object falls from rest near the surface of such a star. How fast would it be moving after it had fallen a distance of 0.013 m? (Assume that the gravitational force is constant over the distance of the fall, and that the star is not rotating.)

A neutron star is an astrophysical object having a mass of roughly 2.8 × 10³⁰ kg (about 1.4 times the mass of the sun) but a radius of only about 12 km. If you were in a circular orbit of radius 320 km (about 200 mi), how long would it take you to go once around the star? Show all steps and give reasoning.

2.00-nF capacitor with an initial charge of 5.35 µC is discharged through a 1.23-kΩ resistor.

(a) Calculate the current in the resistor 9.00 µs after the resistor is connected across the terminals of the capacitor. (Let the positive direction of the current be define such that

> 0.)

How is the instantaneous current related to the potential difference across the capacitor? mA

(b) What charge remains on the capacitor after 8.00 µs?

µC

(c) What is the (magnitude of the) maximum current in the resistor?
A

How would you construct a pendulum clock that is reliable under a variety of temperatures?

The binding energy of an electron in the ground state in a hydrogen atom is about:

A. 13.6 eV

B. 3.4 eV

C. 10.2 eV

D. 1.0 eV

E. 27.2 eV

A 4.4 x 10^14 Hz laser emits a 2.1

a. A large solenoid with a length of 6.7 m and 31000 turns of wire carries an initial current of 4.9 A. The solenoid is aligned so that the magnetic field is produces points to the East. A small coil of wire with a radius of 0.056 m and 2 turns of wire is placed inside this solenoid so that the normal to the plane of the coil is aligned with the axis of the solenoid. The current in the solenoid is then reduced to 0.57 A over a period of 2.4 s. What is the initial magnitude of the magnetic field inside the solenoid?

b. What is the initial magnetic flux through the coil?

c. What is the final magnitude of the magnetic field inside the solenoid?

d. What is the final magnetic flux through the coil?

e. If the coil of wire has a resistance of 31 Ω, what is the induced current in the coil? What is the magnitude of the average electromotive force (EMF) induced in the coil while the magnetic flux is changing?

f. If you are looking at the solenoid and coil from the East (so you are facing West) then the direction of the current in the solenoid must be _____ and the induced current in the coil will be ________

As shown in the figure (Figure 1) , a superball with mass m equal to 50 grams is dropped from a height of hi=1.5m . It collides with a table, then bounces up to a height of  hf=1.0m . The duration of the collision (the time during which the superball is in contact with the table) is tc=15ms . In this problem, take the positive y direction to be upward, and use g=9.8m/s2 for the magnitude of the acceleration due to gravity. Neglect air resistance.

Find the y component of the momentum, pbefore,y, of the ball immediately before the collision.

Find the y component of the momentum of the ball immediately after the collision, that is, just as it is leaving the table.

Find Jy, the y component of the impulse imparted to the ball during the collision.

Find the y component of the time-averaged force Favg,y, in newtons, that the table exerts on the ball.

Find Kafter?Kbefore, the change in the kinetic energy of the ball during the collision, in joules.

1. Using the two equations below, show that the final position of the monkey and ball are the same because of the acceleration due to gravity. At the final position of the monkey and ball, the height of both will be the same. They will also have the same time (t) since they will collide simultaneously. Please arrange your work in an orderly fashion so it may be graded accordingly.

2.      How long would it take a projectile shot from a cannon at 145 m/s, aimed at 45° above the horizon, to reach an altitude of 120 m?

3. If the initial velocity of the above cannon were adjustable, what velocity would be required to shoot the ball exactly a distance of 100 m? Use the following equation and solve:

4. The US Army and Marine Corps use a 39-caliber artillery weapon called the
Ultra-light-weight Field Howitzer (UFH). It fires a projectile at 827 m/s. What is the weapon’s maximum range in combat? (Use the above equation from problem 3)

5.What would be the effect of firing a projectile in space? What would be its trajectory? Explain your answers.?