Recent content by Jolsa

For anyone interested, I have attached the problem (with additional sub-problems that I made up). I have also included the (presumably) correct solution to the questions.

It looks like a typo to me. He does it correctly the first time when he says m\frac{d\vec{v}}{dt}\cdot \vec{v}=\frac{m}{2}\frac{d}{dt}(\vec{v} \cdot \vec{v})=0 Now \vec{v} \cdot \vec{v}=v^2 so it follows that the change in kinetic energy is zero.

Great thinking! But I don't see how you get infinitly many solutions. The solution to the differential equation is e(s)=A\sin(\eta s)+B\cos(\eta s)-s where \eta^2=\frac{\omega^2 \mu}{k} Applying the first boundary conditions yeilds B=0, but the second boundary condition seems to...

How would I calculate the stiffness of each element? k=\frac{L}{dl}k_0 ?

Well, the problem is that the spring does not stretch uniformly. This means that the mass will not be uniformly distributed along the spring, and that the centrifugalforce is different at different points on the spring.

Try looking at the LambertW function :) There's actually a third solution apart from the two you already found, its about -0.767

This is not actually a homework question, but rather a question posed by a friend, so don’t expect the result to be pretty ;) Homework Statement A spring of unstretched length L, spring konstant k and mass M is whirled around with constant angular velocity \omega . Find its new, stretched...

Try using Newtons second law in its "original" form.

For products, the relative error on the measured quantity is equal to the sum of the relative errors. So if z=x\cdot y then \frac{\Delta z}{z}=\frac{\Delta x}{x}+\frac{\Delta y}{y} A more general approach is the formula for uncertainty on a measured quatity f(x,y). The absolute error in...

Are you sure it is the correct answer? Remember you need to consider the moment of inertia of the hole relative to the origin of the disc.

Indeed. Try looking at the first equation again. Can't you use that to eliminate the ratio P/m?

Use energy considerations. First: What is the total change in energy? Second: Find the velocity as a function of P and t and integrate this to obtain the position as a function of time. Now you can use these to equations to eliminate P. Good luck :) Edit: For more info on motion with...

What is the kinetic energy of a rotating body?

What is the magnetic field a distance d from a current carrying wire? Can you exploit the symmetry of the situation?

When you calculate work done from a constant force, you need only think about the force component parallel to the line of motion. What is the forcecomponent parallel the to inclined plane?