Question

Physics...Help..Medal!!

Answer 1

You can tag about like 6 people I would say, but I mean you decide when it's too many people.

Answer 2

IDk your question, I suck at physics, sorry.

Answer 3

hmm... I have to go at a x-mas party so I can't make deductions right now.
@dan815 is very good at physics so I bet he can do it in a shut and open of eyes.

Answer 4

k.....Ta

Answer 5

u*fn = ff
where fn is the normal force the object experiences
calculate the acceleration the block feels due to the plank and gravity

Answer 6

Write the equations along the AB plane and perpendicular to the plane

Answer 7

\[mgsin \theta = \mu_s mgcos \theta + m \omega^2 l\]

Answer 8

hello @cambrige
first of all i wish you a merry merry christmas
okay this question uses the concepts of writing a newton's second law equation and circular motion
okay the question says that the block starts sliding at that instannt when the plank has rotated by an angle theta
just take a look at what i've got
okay so by breaking the force of gravity on the block, we get that the block experiences a force of mgsin theta down the incline and the block exerts a normal force on the plank of mg cos theta . So, the plank also exerts a normal force of mg cos theta
next,
if the plank was frictionless , then the block would move down the plane so the friction would oppose it's relative motion and that's why it would act up the incline
now a very important part of the question we should not forget the centripetal force that is acting down the plane , towards the centre
so the newtons second law equation will be
mg sin theta + Fcent. = mu x N
now there is no force acting in the direction of normal force between the block and the plank so the normal force=mg cos theta (the block and the plank have constant angular velocity so there would be no tangential acceleration and that's why there would be no tangential force i.e. the force in the direction of normal)
so N=mg cos theta
so we get the equation
mg sin theta + m(omega)^2 x l= mu x mg x costheta
so by solving this equation , we get
mu=[mg sin theta + m (omega)^2 x l]/g cos theta
what fifciol did was he took into account the centrifugal force instead of the centripetal force and the centrifugal force is a pseudo force so we cannot take it in the picture
and it is taken into account if we write the newton's second law by standing on the block (i.e. the ref. frame is the block)
so again wish you and all here a very merry x'mas and may this x'mas bring prosperity to you and your family:)
if you don't get any part of this solution, feel free to ask:)