?

1. You are given a number of 10 omega resistors, each capa-ble of dissipating only 1.0 W without being destroyed. What is the minimum number of such resistors that you need to combine in series or in parallel to make a 10 omega resistance that is capable of dissipating at least 5.0 W?

2. A proton traveling at 23.0 degrees with respect to the direction of a magnetic field of strength 2.60 mT experiences a magnetic force of 6.50x10^-17 N. Calculate (a) the proton's speed and (b) its kinetic energy in electron-volts.

For #2, I got 400 km/s in part (a) and I think the formula for part (b) is 1/2mv^2 and I plug 1.67x10^-27 kg for m and 400 km/s for v but I didn't get the correct answer, it should be 835 eV. Do I need to convert something?

An electric field of approximately 100 V/m is often observed near the surface of Earth. If this were the field over the entire surface, what would be the electric potential of a point on the surface? (Set V=0 at infinity.)

I used the formula V=kQ/r where k=8.99x10^9 but I don't know the value of Q and r.

What is the escape speed for an electron initially at rest on the surface of a sphere with a radius of 1.0 cm and a uniformly distributed charge of 1.6x10^-15 C? That is, what initial speed must the electron have in order to reach an infi-nite distance from the sphere and have zero kinetic energy when it gets there?

v=sqrt(something)/m where m supposed to be 9.11x10^-31 kg but what are other variables?

Much of the material making up Saturn's rings is in the form of tiny dust grains having radii on the order of 10^-6 m. These grains are located in a region containing a dilute ionized gas, and they pick up excess electrons. As an approximation, sup-pose each grain is spherical, with radius R=1.0x10^-6 m. How many electrons would one grain have to pick up to have a poten-tial of -400 V on its surface (taking V=0 at infinity)?

An ideal diatomic gas, with rotation but no oscilla-tion, undergoes an adiabatic compression. Its initial pressure and volume are 1.20 atm and 0.200 m^3. Its final pressure is 2.40 atm. How much work is done by the gas?

The best laboratory vacuum has a pressure of about 1.00x10^-18 atm, or 1.01x10^-13 Pa. How many gas molecules are there per cubic centimeter in such a vacuum at 293 K?

The formula is PV=nRT where P=1.00x10^-18 atm, R=8.31, T=293 K, but is the question asking to solve for V or n? Because the answer is 25 molecules/cm^3 and I think I should solve for V which is the Volume but what's the value of n in this case? Is it 6.02x10^23?

1. Two identical piano wires have a fundamental fre-quency of 600 Hz when kept under the same tension. What fractional increase in the tension of one wire will lead to the occurrence of 6.0 beats/s when both wires oscillate simul-taneously?

2. An acoustic burglar alarm consists of a source emitting waves of frequency 28.0 kHz. What is the beat frequency between the source waves and the waves reflected from an intruder walking at an average speed of 0.950 m/s directly away from the alarm?

For both Mechanics and E&M, where can I find them? If it's not on the website, should I buy a book that has it? What's the name of the book?

A certain gyroscope consists of a uniform disk with a 50 cm radius mounted at the center of an axle that is 11 cm long and of negligible mass. The axle is horizontal and supported at one end. If the disk is spinning around the axle at 1000 rev/min, what is the precession rate? (Answer: 0.041 rad/s)

1000 rev/min=16.67 rev/s

My physics teacher doesn't know how to solve this problem and I really need help. Thanks in advance.

I'm a high school junior right now taking 6 AP classes. I don't like Biology at all but it's the only way I can take AP Calculus because my counselor messed up my whole schedule and it's too late to take other classes. And I don't see the benefits of taking the AP Bio exam next year in May. But wouldn't it be a disadvantage if colleges see that I didn't take the AP Bio exam and only took the class of it? I heard that MIT doesn't even give credits for AP Bio at all and it's not gonna be my major at college anyways so what's the point of doing it? And the crazy thing is that I'm also taking AP Physics C right now, it's both Mechanics and E&M. The funny thing is that next year, both AP Bio and AP Physics C exams are gonna be on the same day, on May 13, 2013. My school doesn't offer AP Physics C and I'm self-teaching myself right now, the point is, I don't want to risk too much because of AP Bio since I really want 5 on AP Physics. And one more thing, even if my major isn't Biology at college, will I still be required to take Bio in college? If so, during what year? The first year in college?

1. Find the limit as x approaches infinity for e^2x-1.

2. Find a quadratic function q(x) such that f(x)=(x^2-4)/q(x) has one horizontal asymptote y=-1/2 and exactly one vertical asymptote x=3.

Do many people major in Physics? 10 years later from now, what would be the most popular major? Is it Physics?

A 140 kg hoop rolls along a horizontal floor so that the hoop's center of mass has a speed of 0.150 m/s. How much work must be done on the hoop to stop it?

A 2100 kg truck traveling north at 41 km/h turns east and accelerates to 51 km/h. (a) What is the change in the truck's kinetic energy? What are the (b) magnitude and (c) direction of the change in its momentum?

I know how to do part (a) and I got 7.5x10^4 J but how to do parts (b) and (c)?

For (b), I got 2100(14.17 m/s-11.39 m/s)=5838 and I know that's not the answer.

I know there are particle physics, astrophysics, nuclear physics, quantum physics, etc. Can you name me other subjects? Is there engineering physics as a major? When do you start to major in your school? I've heard that you start to major during your senior year at your high school, is this true?

A single force acts on a 3.0 kg particle-like object whose position is given by x=3.0t-4.0t^2+1.0t^3, with x in meters and t in seconds. Find the work done on the object by the force from t=0 to t=4.0 s.

Okay, so I did the integration. I got (t^4/4-4t^3/3+3t^2/2) from 0 to 4 and the calculator says -32/15. But the answer is 5.3x10^2 J. How do I get there?

A warehouse worker exerts a constant horizontal force of magnitude 85 N on a 40 kg box that is initially at rest on the horizontal floor of the warehouse. When the box has moved a distance of 1.4 m, its speed is 1.0 m/s. What is the coefficient of kinetic friction between the box and the floor?

uk=fk/FN,

where uk is the coefficient and k & N are lower cases, how do you do this problem?

APs are college level courses but what's the name of the subject after AP Physics C? And can high school seniors take that subject to earn college credits? What textbook would you recommend and the name of the author, edition? And do many high school juniors take AP Physics C?

A certain force gives an object of mass m1 an acceleration of 12.0 m/s^2 and an object of mass m2 an acceleration of 3.30 m/s^2. What acceleration would the force give to an object of mass (a) m2-m1 and (b) m2+m1?

From the formula F=ma, what do I need to do?

A customer sits in an amusement park ride in which the compartment is to be pulled downward in the negative direction of a y-axis with an acceleration magnitude of 1.24g, with g=9.80 m/s^2. A 0.567 g coin rests on the customer's knee. Once the motion begins and in unit-vector notation, what is the coin's acceleration relative to (a) the ground and (b) the customer? (c) How long does the coin take to reach the compartment ceiling, 2.20 m above the knee? In unit-vector notation, what are (d) the actual force on the coin and (e) the apparent force according to the customer's measure of the coin's acceleration?