Recent content by naresh

Helium is as close as you will ever get to an ideal gas. I think the intermolecular forces are lesser in Helium than any other gas (most other gases, at least). Your relation between U and T is correct. You are right, we don't know what N is, and we don't know what T is. But we know that...

Yes, using the cosine law will always give you a "correct answer" because the angle lies between 0 and 180 degrees. The sine law is fine, but remember that sin(79.4) = sin(100.6), and you need to be careful with the inverse sine. [In general sin(90-x) = sin(90+x)]. You will need to use something...

Hint: For an ideal gas, the change in internal energy is only a function of the change in temperature.

Well, I think you are going about this the wrong way. If the equations are the same, the acceleration is the same. (Instead of saying the equations are the same if the acceleration is the same). This is because it is easy to write down the equations of motion. You have (correctly) written down...

Yes, good job figuring this out. You should be able to work out the answer from here.

How do you get different directions (both a and A have the same sign in your solution!)? If you ignore the torque on disk B and just look at the forces acting on the centers of mass, do you get different equations of motion for the two disks? Your solution is almost right, except that you...

Your equation for the horizontal forces is perfect. I'm concerned about the equation relating N to mg. Yes, friction opposes the direction of motion (or the direction in which the body is trying to move). If you move too fast, you can imagine that the friction acts downwards. In fact, this will...

I've never actually done the experiment, so my answers may be way off. 1) That sounds right. You'd need vapour to do the experiment. 2) No idea about the thermocouple. 3) The definition of eV is that it is the energy acquired by an electron when accelerated through a potential of 1 V (hence...

1. I think treating it as a constant charge density is fine with the problem stated the way it is. When you say \rho_{0} with a subscript, it is usually meant to be constant. The problem does say "constant, positive charge density" :wink: Being "different at different points" is not constant...

Since the torque is a vector, whether it is "positive" or "negative" depends on how you choose your axis. You are right, the torque points towards you. Asking whether this is positive or negative, without knowing the coordinate axes, is meaningless.

It is good to clearly define an axis. In the next step, you have equated the forces along the x direction. What you should do next is to equate forces along the y direction, no? In other words, can you check again if this equation is correct? Finally, you should think about what direction the...

I'm glad it worked, but do you understand why it worked? Why should the sum of the kinetic energies give you the potential energy?

Well, you know the distance and you want the time taken to travel the distance. What else would you need to know to calculate the time?

Yes, it is fine. You might want to be more specific about part A. The wall is the source of the centripetal force all right, but the wall is not a force.

The phase φ in simple harmonic motion is basically your choice of time origin, i.e. it tells you what the displacement and velocities are at t = 0. For example, at t=0, if you started the motion at x = -A, you would get φ = π. If your initial condition was x = 0, you have φ = +/- π/2. (Whether...