Physics 8.5 Rotational Kinetic Energy (12 of 19) P.E. Converted to Rotational K.E. 1

In this video I will find the v(final)=? of a m=5kg mass.

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[aadithephysicsguru]

Hello there! There is this problem that I THINK deals with rot. kinetic energy that I am stuck on. Since your videos are super helpful, I thought I could ask you. Here it is:

A trebuchet is a device used during the Middle Ages to throw rocks at castles. Model it as a stiff rod of negligible mass 3.00 m long and joining objects of mass 60.0 kg and 0.120 kg at its ends. It can turn on a frictionless horizontal axle perpendicular to the rod and 14.0 cm from the object of larger mass. The rod is released from rest in a horizontal orientation. Find the maximum speed that the object of smaller mass attains.

Thanks!!

[ptyptypty]

along the same line as my previous post.... I'm also Amazed at how the MASS of something does NOT matter when it comes to BRAKING DISTANCE of a Vehicle... be it a Semi Truck or a it's only the Coefficient of Friction of the Tires on the Road that matter.... if a Semi Truck and a Motorcycle are speeding along at 100 MPH.. and they are side by side.. and they both have the same Coefficient of Friction for their TIRES and then they both slam on their brakes and skid to a stop... THEY BOTH STOP IN THE SAME DISTANCE.... by the way.. Stopping Distance = [(1/2)(Vo)^2]/(g*u). Mu = u g = 9.8 Vo = Initial Velocity of vehicle. NOTICE.. there's NO Mass in the equation. Again, So COUNTER Intuitive.... thanks for letting me Blab here, Michel!! Great video!!

[Ayayron_e]

very well explained. Thank you, professor.

[ptyptypty]

I'm always amazed with a problem like this.... because the RADIUS of the Drum or disk or what have you, DROPS OUT OF THE EQUATION.... the radius drops out in the Kinetic Energy equation of Rotation.... the Drum could have had a radius of 1 KILOMETER.. and yet only the MASS is what matters... that is so Counter Intuitive!!... interesting to note that when it comes to Rotational MOMENTUM... the radius does NOT drop

[andrewjustin]

Mr. Michel, I'm a little perplexed because when the system begins to move, there's not only the translatory kinetic Energy of the hanging and the rotational kinetic energy of the cylinder, but the cylinder also moves towards the pulley while the pulley also posseses the rotational kinetic energy, don't they? Please clarify!

[NotLegato]

what am i doing wrong? if I=0.025kgm^2 and torque is 4.9Nm, angular acceleration would have to be... 245 radiand per second squared and that's kind of ridiculous.

e: I'VE SOLVED IT: the tension in the rope is *not* equal to the weight of the block: mg - T = ma, torque = I * a/r. torque comes from the tension, so I * a/r = Tr => T = I * a/r^2, after which you can solve it fully. the main takeaway is that the moment of inertia and the fact that it's not static affect the tension in the rope.

[kyleabrahams]

Hi Prof. Michel, have you done videos with rotational/angular motion including(torque, work done and power)?

[batuhancoskun]

Sir v final should be 4.43 ı think bu ın your answer its different. I solved your equation many times but everytime ı found 4.43. Am ı right or wrong?

[sandrav]

Hi!
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Thank you for all your videos!