haruspex's latest activity
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haruspex replied to the thread Equilibrium Position of a Hanging Candy Cane.Doh. I had written ##\tan(y)=B/A## but mistranscribed it, then only half adjusted what followed. -
haruspex replied to the thread Equilibrium Position of a Hanging Candy Cane.Yes. In the more tricky case of ##A\sin(x)+B\cos(x)=C##, set ##\tan(y)=A/B##, producing...
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haruspex replied to the thread Equilibrium Position of a Hanging Candy Cane.It is always possible that the given answer is wrong, but you do not say what answer you are getting, so we cannot tell. Wrt solving...
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haruspex replied to the thread Writing a vector parallel and normal to a unit vector ##\hat n##.Generalising somewhat, suppose in an n-dimensional vector space we wish to represent the vector ##\vec v## as a linear combination of...
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haruspex replied to the thread Finding the charge on pith balls.Why would you set the electrostatic force equal to the gravitational force? Are they in the same direction?
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.It is interesting to see the relationship to the parallel axis theorem. Consider an element ##\delta m## at displacement ##\vec s##...
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.As I wrote in post #11, it was rather misleading for me to have described it as angular acceleration in post #9. Hang on to the fact...
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.You don’t have to worry about the moment of inertia. The object is not actually rotating. Consider a point mass m moving at velocity...
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.Using the leading caster as the axis, the angular acceleration is ##a/(H/2)## Net torque about the leading caster...
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.It is always valid to work in an inertial frame; no exceptions. And it gives the same answer. It is also valid to work in any...
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haruspex replied to the thread 2D rigid body mechanics: force applied on sliding cart.The least confusing approach is to work in an inertial frame and take moments about the mass centre of the cart. What does that give...
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haruspex replied to the thread Projectile motion with ##N## bounces on the ground.Your original approach strongly suggested that limiting value, it just wasn't a valid proof.
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haruspex replied to the thread Projectile motion with ##N## bounces on the ground.I do apologise, I have taken you the wrong way. Just realised there should have been a caveat where you cancelled ##D_{AB}## in post...
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haruspex replied to the thread A lead bullet gets embedded in a lead block.I agree, the problem is quite ambiguous. Immediately after impact, the whole object doesn’t have "a temperature". The bullet and...
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haruspex replied to the thread Projectile motion with ##N## bounces on the ground.No, nothing like that. As mentioned, might as well use N rather than N+2. They’re both going to infinity...