Recent content by physicsisgreat

I'm not sure I can quite agree with you on this. As long as you correctly take into account the fictitious forces acting on a non-inertial frame, it doesn't come to my mind any example of non-validity of Newton's laws: what am I missing?

This is fun :D I also would add the following to see if you agree again with me. Imagine you are inside a car which is accelerating and a friend of yours is still outside the car. From the frame of the Earth his energy is constant and the total force acting on him/her is 0, so W = 0 too. Since...

I understand that this is the crucial point, but my reasoning is: if no horizontal force would be applied on the box, the box would feel no acceleration. But the box is decelerating, so some force is applied on it, and the only force acting on it is friction. I also have to add: "The principle...

Homework Statement A truck is moving at constant velocity v0 with a box of mass m on it. Suddenly it starts decelerating until its velocity becomes zero. Between the box and the truck the is a force of friction and the deceleration of the truck is sufficiently slow to allow the box not to start...

Thank you very much haruspex! :)

Mmh, following the impulse-momentum theorem J = ΔP I would say that v0 = J / m. At the same time I wonder: can this be true? Can the velocity of the center of mass of the rod be independent from the point in which the impulse is applied?

Hi, I edited my post adding the factor missing and an equation about ω (which I actually used later in my attempt at a solution). I cannot give another equation about v0 though, as it is exactly what I am looking for! :)

Homework Statement I have a rod of mass m and length l on a table without any kind of friction. I give it an impulse J in any point of distance d from the center of the rod, parallel to the table and perpendicular to the rod. Find the angular velocity ω and the velocity of the center of mass...

Thank you very much for your replies! So it seems like the information ħ = 1 is actually not needed at all: if I get it right, we just use KB = 1 to use K instead of J and then use Å instead of m. Right? :) Thank you again! ^ ^

Homework Statement Units of the problem are chosen to be such as KB = 1 and ħ = 1 so that energies are expressed in Kelvin and lengths in Å. The professor says the resulting value of ħ2 / 2 m for a 4-He atom is 6.0599278: how is that possibile? Homework Equations Natural units websites give...