# Search results

1. ### Proof using Gauss' Law

A = 2(pi)rL E[2(pi)rL] = Q/ε E = Q/ε[2(pi)rL] E = λ/2(pi)εr Is this correct?
2. ### Proof using Gauss' Law

Homework Statement A long, thin, straight wire of length L has a positive charge Q distributed uniformly along it. Use Gauss' Law to show that the electric field created by this wire at a radial distance r has a magnitude of E = λ/(2πεor), where λ = Q/L. (Hint: For a Gaussian surface, use a...
3. ### Electric Fields and Point Charges

Homework Statement Suppose you want to determine the electric field in a certain region of space. You have a small object of known charge, and in an instrument that measures magnitude and direction of the force exerted by object by the field. (a) The object has a charge of +20.0 C, and...
4. ### Weather Balloon

nevermind, i got it! thank you!
5. ### Weather Balloon

where did you get the 0.33 from?
6. ### Temperature Change

2 degrees is right thank you!
7. ### Temperature Change

Homework Statement The following table shows the daily high tem- peratures for a week in May. Determine the change in temperature each day. Sun. 76◦ Mon. 72◦ Tues. 80◦ Wed. 75◦ Thurs. 75◦ Fri. 74◦ Sat. 78◦ Find the net change in temperature (the...
8. ### Weather Balloon

Homework Statement A weather balloon is designed to expand to a maximum radius of 30 m when in flight at its working altitude where the air pressure is 0.033 atm and the temperature is 95 K. If the balloon is filled at atmospheric pres- sure and 462 K, what is its radius at lift-off...
9. ### The Internal Energy of Neon Gas

So, d = P X MM/RT d = (0.7 atm)(20 g/mol)/(8.31 J/mol*K)(200 K) d= 0.008423586 2 L * 0.008423586 = 1.684717208E-5 kg KE = 1/2(1.68E-5)(499.227 m/s)^2 = 2.09 J (WRONG ANSWER) AM I USING THE WRONG UNITS OR DID I DO A MATH ERROR???
10. ### Car Tire Pressure

Oh...I got it. Thank you!
11. ### Car Tire Pressure

If you divide: 57.2 psi/0.81 = 70.6 psi ALSO NOT THE RIGHT ANSWER! The right answer is 55.8986 psi, so the pressure does get smaller.
12. ### Car Tire Pressure

I'm assuming multiply: So, 57.2 psi X 0.8102143758 = 46.3 psi BUT THIS IS NOT THE RIGHT ANSWER!
13. ### Car Tire Pressure

The ratio of T1/T2 = (257 K)/(317.2 K) = 0.8102143758
14. ### The Internal Energy of Neon Gas

Homework Statement The internal energy of a monoatomic ideal gas such as neon is simply the total kinetic energy of all its atoms. What is the internal energy of 2 liters of neon at a temperature of 200 K and pressure of 0.7 atm? Homework Equations PV = nRT KE(ave) = 3/2kT U =...
15. ### Car Tire Pressure

Homework Statement A car tire gauge is used to fill a tire to a gauge pressure of 42.5 lb/in2 on a cold morning when the temperature is -16 C. Atmospheric pressure is 14.7 lb/in2 and 0 C = 273 K. What would the tire gauge read when the tire has been heated up to 44.2 C? Homework...

17. ### Rolling Cylinders

I'm sorry but what does this mean? I don't understand what you just said.
18. ### Rolling Cylinders

well then: y = (1/2)(9.8)(0.368)^2 y = 0.66 m BUT this answer is wrong! The answer is 0.25 m. Am I using the right acceleration and time?
19. ### Rolling Cylinders

I still don't know which equation to use! Is it: v = -1/2gt t = 0.368 and then what? or am I still off?
20. ### A Spinning Top and Rotation Dynamics

YES!!! Thank you very much. That equation has been in front of my eyes this whole time.
21. ### A Spinning Top and Rotation Dynamics

The only equation I can think of is: w^2 = wi^2 + 2(alpha)(theta) so: w^2 = 2(5570 rad/s2)(.80) w = 94.4 rad/s BUT that is not the right answer!
22. ### Rolling Cylinders

Homework Statement A thin cylindrical shell and a solid cylinder have the same mass and radius. The two are released side by side and roll down, without slipping, from the top of an inclined plane that is 1 m above the ground. The acceleration of gravity is 9.8 m/s2. Find the final linear...

24. ### A Spinning Top and Rotation Dynamics

I can't think of any equation that can give me angular speed from angular acceleration without time.
25. ### A Spinning Top and Rotation Dynamics

Homework Statement A spinning top has a moment of inertia of 0.0004 kg*m^2 and is initially at rest. It is free to rotate about a stationary axis. A string, wrapped around a peg along the axis of the top, is pulled in such a manner as to maintain a constant tension of 5.57 N in the string...
26. ### Space Station Design

Oh...okay, so: astronaut's speed: 56.17472741 m/s + 5 m/s a = v^2/r a = (61.17472741 m/s)^2/322 m = 11.62223624 m/s^2
27. ### Space Station Design

Homework Statement Part 1: You want to design a large, permanent space station so that no artificial gravity is necessary. You decide to shape it like a large coffee can of radius 322 m and rotate it about its central axis. The acceleration of gravity is 9.8 m/s2. What rotation speed...
28. ### More torque yay

More torque yay!!! Homework Statement A horizontal bar with a mass m suspended from one end is held by a cord with tension T, fastened at a distance D from the end of the bar that is attached to a wall with a frictionless pin. What is the torque about the pin exerted on the bar by the cord...
29. ### Torque, torque, torque

Homework Statement A rod can pivot at one end and is free to rotate without friction about a vertical axis. A force F is applied at the other end, at an angle theta to the rod. If F were to be applied perpendicular to the rod, at what distance d from the axis of rotation should it be applied...
30. ### A Block Sliding Down an Incline

Homework Statement Starting from rest, a 5 kg block slides 2.5 m down a rough 30 degree incline. The coefficient of kinetic friction between the block and the incline is 0.436. The acceleration of gravity is 9.8 m/s2. Find the work done by the force of gravity. Find the work done by...