Rotational dynamics Definition and 277 Threads

A Right Circular uniform Solid cone of mass m and semi vertical angle a(alpha) is placed over a rough horizontal surface. Assuming friction to be sufficient to prevent slipping, find the minimum force that can be applied at the tip of the cone such that it just topples.

Hello, I was able to solve this problem fine, but I had a question about it: "A disk 8.00 cm in radius rotates at a constant rate of 1200 rev/min about its central axis. Determine (a) its angular speed, (b) the tangential speed at a point 3.00 cm from its center, (c) the radial...

dear guys, i am very depressed since i cannot do these problems...please help me with them.. 1)a solid cylinder of mass 20kg and radius 0.12m rotating with initial angular speed of 125ms-2 is placed lightly(ie without any translational push) on a horizontal table with co-efficient of kinectic...

Hey guys, i don't know why its always two or three problems on my homework that always stump me. Any help and tips are appreciated 1) A wheel with a weight of 393N comes off a moving truck and rolls without slipping along a highway. At the bottom of a hill it is rotating at an angular...

Can anyone help me with where to begin ? ? ? Turning a doorknob through 1/6 of a revolution requires 0.1 J of work. What is the torque required to turn the doorknob? i know that T = F x r what is the force and radius ?(is radius 3/6=1/2??)

I guess I'll introduce myself as well: My name is, well, my username, but you can call me Drew (most people do). I'm 18 (a senior in high school) and in an AP Physics II class focusing on mechanics. I posted something in the advanced physics forum that should probably have been moved here, so...

A skinny student (40 kg) sits on a stool that can rotate, holding two 8 kg bowling balls with his arms out stretched. The stool weighs 20 kg. The student and stool are spun such that they have an angular velocity of 2 rad.s-1. When the student pulls his arms in towards him, what happens to...

1.A uniform Disc of Radius R is rotating in its own plane with angular velocity w when it is placed flat on a rough table. If u the coefficient of sliding friction is independent of velocity show that the time taken for the disc to come to rest is (3RW)/(4ug). How does the kinetic energy of...

Ok I'm in desperate need of some direction! I have the following question in which I must answer twice once using rotational dynamics and then again using Conservation of Mechanical Energy. Question: A massless string is wrapped around a solid cylinder as shown in the diagram at the right...

Wanted to check this question also: A meter stick of mass 0.44 kg rotates, in the horizontal plane, about a vertical axis passing through the 30 cm mark. What is the moment of inertia of the stick? (Treat it as a long uniform rod) Answer: I = 0.1628 kg.m^2 Correct??

Hello there, I've got a problem here. A solid cylinder of radius 0.8 m and mass 4.0 kg is at rest. A 4.0 N m torque is applied to the cylinder about an axis through its centre. Calculate the angular velocity of the cylinder, in rad s-1 , after the torque has been applied for 2.0 s. how do...

I have a couple questions could someone help? I tried everything and I just don't understand what's going on. Thank you sooo... much! :D 1)A cylinder is rotating about an axis that passes through the center of each circular end piece. The cylinder has a radius of 0.0600 m, an angular speed...

1) A centrifuge rotor rotating at 10,300 rpm is shut off and is eventually brought uniformly to rest by a frictional torque of 1.20 m-N. If the mass of the rotor is 4.8 kg and it can be approximated as a solid cylinder of radius .0710 m, through how many revolutions will the rotor turn before...

:confused: A solid sphere (I=(2/5)MR^2) with a radius R=0.10m is attatched to a massless rope by a frictionless axle that passes through the center of the sphere. The rope passes over an ideal pulley and is connected to a 1kg block. The sphere has a mass of 2kg. The surface has a meu that...

Why do we use the angle as the base quantity in rotational dynamics instead of, perhaps, arc length? Is it because angular displacement is easier to measure? Would it make any sense to use arc length?

I tried to do this problem with related rates and calculus. We have not done physics with calculus, however. The other way I thought about was using the angular velocity of the board when the stick is taken away. I cannot seem to solve it though. A common physics demonstration consists of a...

A rope is wrapped around a wooden sylinder with I=2.9 and radius = 0.25m A 50 kg crate is suspended to the free end of the rope and is pulled upwards with an acceleration of 0.80 m/s*s A crank handle is attached to the axle of the wooden cylinder and when turned rotates about the axle in a...

Please could someone check my answers to the following and advise me on any of the bits I'm stuck on. Thanks ===== Q. A disk of radius a and mass m is suspended at its centre by a vertical torsion wire which exerts a couple \fontsize{5} -c\theta on the disk when it is twisted through an...

A wrecking ball (weight = 5400 N) is supported by a boom, which may be assumed to be uniform and has a weight of 3800 N. As the drawing shows, a support cable runs from the top of the boom to the tractor. The angle between the support cable and the horizontal is 32°, and the angle between the...

hi i need help understanding what to do with the information that was given in the problem if u could point mein the right direction i would greatly appreciate it. thank you An invered "A" is suspended from the ceiling by 2 verticle ropes. Each leg of the "A" has a length of 2L and a weight...

hi i need help understanding what to do with the information that was given in the problem if u could point mein the right direction i would greatly appreciate it. thank you An invered "A" is suspended from the ceiling by 2 verticle ropes. Each leg of the "A" has a length of 2L and a weight...

Hello, I have a problem dealing with torques and acceleration. I am sure I solved it right but when submitting the answers, I get the response "Incorrect" :cry: The problem: A wheel of radius 2 m, mass 53 kg, and moment of inertia (3/4) (53 kg) (2m)^2 about the center of mass is mounted...

Here is the question (it's part of a lab): "From your lectures in mechanics you should be able to derive: \alpha = \frac{mgr}{I+mr^2} This equation ignores the effect of the pulleys and the mass of the connecting string" The lab was basically setting up a mass on a string over a pulley...

Here's the problem: diameter = 3.45 cm angular speed = 11.4 rad/s angular deceleration = -.96 rad/s How far does the coin roll before coming to a stop? How would I set this problem up? Thanks!

I really have no idea how to go about doing this one... Any help is well appreciated! Thanks! What is the angular acceleration of the rectangle in (attachment) if a torque of 13 Nm is applied about (a) the x-axis (b) the y-axis and (c) the z axis (through origin and perpendicular to the...

im doing questions from "Calculations for A-Level Physics" answers not provided for this Q. Question : A grinding wheel of radius 0.080m is driven by an electric motor at a constant speed of 50 rps. A piece of steel is pressed against the outer rim of the wheel, producing tangential force...

I have no clue on this, I am stumped anyone have an idea. a platform is rotating at an angular speed of 2.2rad/s.A block is resing on this platform at a distance of 0.30m from the axis. The coefficient of static friction between the block and the platform is 0.75. Without any external torque...