# Tagged Questions

Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather than giving it away outright. Please READ THE GUIDANCE IN META before asking homework questions.

224 views

### Newton's third law does not apply to the kinetic energy formula?

Here is a classic problem: A 60kg boy and a 40kg girl are sitting in front of each other on skateboards on a frictionless horizontal surface. The boy pushes the girl and the girl gains a velocity ...
363 views

### How would I explain Ohm's Law in terms of Electrical Fields and Force?

In terms of current, resistance, and voltage, it's easy: Ohm's Law is the relationship between current, voltage, and resistance of a circuit. Boom, simple as that. How could I put this in terms of $E$ ...
269 views

127 views

63 views

### Optics & Law of Cosines

I'm supposed to use law of cosines on $S_1S_2P$ in the following diagram that relates to a lens: To arrive at the following equation:  \frac{r_2}{r_1} = [1 - 2(\frac{a}{r_1})sin(\theta) + ...
33 views

### Proof about Newton: Homework [duplicate]

a mass hangs from three ropes (as shown in the Picture) can someone pleas help me with this?
119 views

### Finding possible values of $L_x$ given $L^2$

Here's a homework problem I'm working on. I am not asking for the answer, but any guidance or comments on the approach are appreciated. Given that a measurement of $L^2$ for a free particle has ...
168 views

### About partially polarized light and the degree of polariztion

When I was taking Optics course, I found there were several questions about polarization of light. I use the textbook of Hecht. It seems that the definition of degree of polarization may be not so ...
102 views

### What happens when you give excess energy to an atom?

So this is my question: An electron in a hydrogen atom in its ground state absorbs energy equal to the ionisation energy of $Li^{2+}$. The wavelength of the emitted electron is? I started off by ...