Recent content by Adjoint

Thanks. :smile:

We can use dimensional analysis in two ways: 1. To verify if an equation is incorrect: Suppose you have an equation and you want to make sure it is dimensionally correct. For this, you must know the dimension of all physical quantities in the equation. Plus you should also know the dimension of...

This is one very basic question. But I just need to confirm if I understood it right. Suppose a particle moves along a curve and crosses Δs path in Δt time. Then we can say the velocity of the particle is \vec{v} = ds/dt \hat{u} Where \hat{u} is tangent to the curve. Also if the same particle...

Thank you. So if I am in an empty space with nothing to compare with then just by proper experimentation I can tell if I am rotating or not. But then as I am rotating, I can imagine a reference frame which is not rotating, right? I can call this reference frame the absolute frame which never...

Well I thought we measure rotation with respect to a reference frame. So rotation of an object should seem different from different frames. Would you please explain why we consider rotation to be absolute? Doesn't it depend on reference frame of the observer? So should we assume that anything...

I need some clarification here. We know that the Earth rotates about it's own axis and also around the Sun. Now my questions are: 1. In the geocentric model of Ptolemy the Earth was at the center of a circle while the planets (and sun) moved along epicycles and the centers of those epicycles...

Welcome to PF! As a general rule, You should show your work (ie write what you have done so far to solve the problem) and also use the homework template while posting in Homework section. Please read https://www.physicsforums.com/showthread.php?t=686781 and...

Oh I should have written vy = 2xvx That was a super silly mistake. :shy: Thanks!

Homework Statement A particle is moving along a parabola y = x2 so that at any time vx = 3 ms-1. Calculate the magnitude and direction of velocity and acceleration of the particle at the point x = 2/3 m. Homework Equations Kinematics The Attempt at a Solution vx = 3 (given) y = x2 so vy =...

I hadn't thought this way but now I see that can be another approach. Thank you.

At first, I also thought how can there be a collision? But later I also had this Oh! I see moment. :tongue2:

Thanks! We have, vBt + d = vAt - \frac{1}{2}at2 → \frac{1}{2}at2 + (vB - vA)t + d = 0 Solving for t, t = \frac{-(v_B - v_A) \pm \sqrt{(v_B - v_A)^2 - 4.\frac{1}{2}ad}}{2.\frac{1}{2}at^2} If we want a solution not to exist then (vB - vA)2 - 2ad < 0 → (vB - vA)2 < 2ad Now we know if x...

I can solve the time of collision by taking this inequality as an equality. Is that what you mean?

Well, I think there can be a collision if car A was moving with a much higher velocity than car B. So even after being behind and applying break, it might hit car B.

Homework Statement Two cars, A and B are traveling in same direction with velocities vA and vB. When car A is distance d behind car B, the breaks on A are applied, causing a deceleration a. Show that to prevent a collision between A and B, it is necessary that, vA - vB < \sqrt{2ad} Homework...