1.) Motors and generators  

a) In a homopolar motor (like Faraday’s motor), what happens to the motion if the current is reversed?

b) Who was William Sturgeon and what was his connection to motor improvement?

c) What is the voltage induced in a generator with 974 turns, an area of 195 mm² turning at a rate of 42 rpm with a constant field of 0.0209 T?

A U-shaped tube is filled mostly with water, but some vegetable oil has been added to both sides of the U tube. On the right side of the tube, the depth of oil is 7.00cm . On the left side of the tube, the depth of the oil is 2.80cm . The density of the water is 1.00

a) A ball of charge +q is placed on the x-axis at x=0. A second ball of charge +16q is placed on the x-axis at x = -2a. A third ball , with a charge that has a magnitude of q, is placed on the x - axis at a n unknown location . If the net electrostatic force exerted on the ball at the origin due to the other two balls has a magnitude of 5kq^2/a^2, what is the location of the thir d ball and the sign of the third ball

Discussion Question 1:

Discuss the differences between the Einstein’s Theory of Relativity and Classical Physics Theory (i.e. Galileo and Newton, etc.)

Discussion Question 2:

Discuss the wave-particle duality of light and its implications. What are possible industrial applications?

Three uniform sticks, each of mass m, are placed on the floor as follows: stick 1 lies along the y axis from y = 0 to y = 3.5 m , stick 2 lies along the x axis from x = 0 to x = 3.5 m , stick 3 lies along the x axis from x = 3.5 m to x =7.0 m .

A.Find the x-coordinate of the center of mass of the sticks.

B.Find the y-coordinate of the center of mass of the sticks.

C.How would the location of the center of mass be affected if the mass of the sticks were doubled? Explain

A car starts from rest at a stop sign. It accelerates at 2.0 m/s2 for 6.3 seconds, coasts for 3.0 s , and then slows down at a rate of 1.5m/s2 for the next stop sign.

a) How far apart are the stop signs?

Express your answer with the appropriate units.

Physics Question:

Write a brief (one to two paragraph) essay discussing what a physicist means by a "force". Include a discussion of what the different kinds of forces are that we have talked about in this class and some of their properties.

A whale swims at a constant velocity of 15 m/s southeast for 10 seconds, slows to a stop at a rate of 3 m/s^2, and then accelerates northwest at a rate of 2 m/s^2 for 5 seconds.

(a) sketch the velocity versus time t for the entire motion. Assume the motion started at time t=0 seconds;

(b) how long did the motion described last?;

(c) find an expression of the whale's velocity as a function of time for the entire motion;

(d) find an expression for the whales acceleration as a function of time for the entire motion;

(e) sketch the acceleration as a function of time;

(f) find an expression for the whale's average velocity over any time interval [0,t] during the motion;

(g) find the expression fo the whale's displacement as a function of time; and

(h) sketch the displacement versus time for the entire motion.

A. A sphere and a cylinder roll down an inclined plane, started from rest at the same time. They have the same radii, but not the same mass. Does one reach the bottom first? If so, which? Explain your reasoning.

B. Two spheres roll down an inclined plane, starting from rest at the same time. Sphere A has radius R and mass m. Sphere 2 has radius 2R and mass m. Does one reach the bottom first? If so, which? Explain your reasoning.

An electron moves with a speed of 3.0

An automobile has a vertical radio antenna 1.40 m long. The automobile travels at 56.0 km/h on a horizontal road where Earth's magnetic field is 50.0 µT, directed toward the north and downward at an angle of 65.0° below the horizontal.

Calculate the magnitude of this induced emf.

...........MV

How is the speed of an object in space measured? Also more importantly how do you measure your own speed in space? On the road we use a speedometer which tells us the speed easily. How is it done in space?

a) Describe how a circular turn (or a circular coil) constitutes a dipole magnet.

b) Consider a solenoid of N turns with a radius r and length l, and carrying a current I. What is the magnitude of magnetic field inside the solenoid (but not near the ends)? Does this magnitude depend on distance the center of the solenoid? ?

c) What is the magnitude of magnetic field outside the solenoid (but not near the ends)?

Discuss the main differences of direct gap and indirect gap semi-conductors.