# Recent content by Bryson

1. ### Vertical Kinematic Problem

Homework Statement A stone is dropped of a cliff. A second stone is thrown down the cliff at 10 m/s at 0.5s after the first stone. When do the stones cross paths? Homework Equations Yf = vt + at^2/2 The Attempt at a Solution My logic is the set the final position Yf equal for both stones...
2. ### Throwing a rock up a hill

Yep, got it. I was on the wrong track. . . I would shoot myself in the foot, but instead I may get rid of it altogether! Thanks for the help and quick replies.
3. ### Throwing a rock up a hill

Getting rid of time; the only way I see that is if I substitute t = \frac{x_f}{v_x} , giving us y_f = x_f tan(\theta) + \frac{1}{2 v_x^2} a_y x_f^2. Perhaps I do not understand, we do not know y_f , nor x_f .
4. ### Throwing a rock up a hill

I tried this but here is what I got: y_f = x_f tan(\phi - \theta) + \frac{1}{2}a_y t^2. Still too many unknowns though, assuming my algebra and logic is correct of course.
5. ### Throwing a rock up a hill

Homework Statement I was tutoring the other day, when we came across a problem that had me stumped! A person standing on a hill that forms an angle \theta = 30^o wrt to the horizon, throws a stone at {\bf v} = 16 m/s up the hill at an angle \phi = 65^o wrt to the horizon. Find y_f...
6. ### Lagrangian for a free particle expansion problem

Hello, this is probably one of those shoot yourself in the foot type questions. I am going through Landau & Lifshits CM for fun. On page 7 I do not understand this step: L' = L(v'^2) = L(v^2 + 2 \vec{v} \cdot \vec{\epsilon} + \epsilon^2) where v' = v + \epsilon . He then expands the...
7. ### Horizontal Pulley Question [Forces]

Perhaps, think about a force diagram. You have one force going downward and one upward. Draw it out, then solve for your unknown.
8. ### Question about eigenvector and identity matrix

Every vector is an Eigenvector of the identity matrix. Perhaps I do not understand what your saying. . .
9. ### Proving properties of the Levi-Civita tensor

You are absolutely correct! The definition of the Levi-Civita (i.e. swapping (non-cyclical) => minus sign).
10. ### Centrifugal Force, Centripetal Force, and Space

The centrifugal force is not an inertial reference frame, as you said fictitious.
11. ### Horizontal Pulley Question [Forces]

What do you think the acceleration of the falling object is?
12. ### How many ways to put 100 distinguishable particles into 6 boxes?

Not to sound redundant, but the key word here is: combinations
13. ### Elementary Wave Functions

Do you need to use Mathematica? Just use integral table or or solve it as mentioned above. In all my QM courses, we never used Maple, or Mathematica.
14. ### Problem with integrals

Okay, also note that \int \cdots \int f(\vec{x}) \delta(\vec{x} - \vec{x}_o) d^Nx = f(\vec{x}_o). This can allow you to fix some variables. My next question is, are we integrating from -\infty \rightarrow \infty ? If the variable being integrated is not within the bounds, we can simplify...
15. ### Problem with integrals

What have you attempted? Do you understand the properties of the delta function?