Angular acceleration Definition and 566 Threads

Homework Statement We did this question today in class, but looking back at it, I'm kind of confused. Two identical dumbbells are formed by placing equal point masses at either end of two identical light (ie. massless) rods. The rods are pivoted so that dumbbell A rotates around the centre...

Homework Statement A physical pendulum oscillates through small angles about the vertical with the angle, measured in radians, obeying the differential equation d2θ/dt2 = -4πθ. What is the period of the oscillation? Homework Equations T = 2π √(L/g) The Attempt at a Solution I...

Homework Statement Calculate the angular acceleration and angular velocity of a 2kg object rotating in a circle of 1.5m radius in a time of 3s. Homework Equations w=v/r 2*pie*r The Attempt at a Solution Hi all, every attempt so far has been a failure, I just can't work out...

I'm not sure if this goes in there since it's a question about an experiment involving classical mechanics. So I've done an experiment where I have determined for a rotating cylinder, its angular acceleration as I let a weight attached to it drop. Now each of these angular accelerations have an...

Homework Statement CD is playing for 74 min, starts at angular speed of 480 rpm then slows to 210rpm. what's the magnitude of the angular acceleration Homework Equations angular acceleration =ω/ t The Attempt at a Solution i converted the rev to rad then min to sec then divided...

Homework Statement Calculate the angular acceleration in radians per second squared of a wheel that starts from rest and attains an angular velocity of 545 revolutions per minute in 1.00 minute. (a) What is the angular displacement in radians of the wheel during the first 0.500 min? (b) During...

Homework Statement A CD has a playing time of 59.8 minutes. When the music starts, the CD is rotating at an angular speed of 460 revolutions per minute (rpm). At the end of the music, the CD is rotating at 202 rpm. Find the magnitude of the average angular acceleration of the CD. Express...

Torque = 2m * 50N M.o.I = (400kg * 2m^2)/2 a = 1/8 rad/s^2 = 0.019894368 revs/s^2 I don't even know which formula to use But I tried this one ω= ω0 + αt 0.5rev/s = 0 + 0.019894368rev/s^2 * t t = 23.132 That's seems like a lot of time... not sure if it's right.

Homework Statement m=6kg r=0.18m Fapp=33N I'm struggling to understand how to answer this question and correlate the linear force applied to rotation without being given the coefficient of friction causing the rotational motion. The question states that a solid sphere of 6kg is...

Angular acceleration - Please check if this is correct and... Homework Statement Question: Each of the tires of a car makes 85.0 revolutions as the car reduces its speed uniformly from 90.0 km/h to 60.0 km/m, The tires have a diamater of .900m. Find initial and final angular...

So knowing knowing radius and mass of the object, what is the equation to find angular acceleration?

Homework Statement See attached Homework Equations Ok..Im having difficulty with this problem. I don't see what m has to do with angular accerleration. The Attempt at a Solution I believe the equation to use for this is a=rα ? I just can't get there..any help would be great...

Good day to all. I have worked out a problem concerning angular acceleration and velocities but I am not sure if what I have done is correct. I have attached all the worked out problem as a pdf as I wanted it to be as clear and concise as possible, especially when someone is taking time from...

A CD has a playing time of 74.2 minutes. When the music starts, the CD is rotating at an angular speed of 488 revolutions per minute (rpm). At the end of the music, the CD is rotating at 215 rpm. Find the magnitude of the average angular acceleration of the CD. Express your answer in rad/s^2...

Homework Statement Two forces are applied to a pulley with a moment of inertia I = .15kg*m^2. The pulley is mounted so that its frictionless axle is fixed in place. 1) What is the angular acceleration of the pulley? 2) If the pulley starts from rest, how long does it take to undergo...

angular acceleration of a fan! Homework Statement An electric fan is turned off, and its angular velocity decreases uniformly from 500 rev/min to 200 rm rev/min in 4.00 s. Find the angular acceleration in rev/s and the number of revolutions made by the motor in the 4.00 interval...

Homework Statement a disk rotates with constant angular accel. the initial angular speed of the disc is 2pie rad/s. After the disk rotates through 10pie rad, the ang speed is 7pie rad/s. Homework Equations a. what is the mag of the angular accel? The Attempt at a Solution...

Homework Statement A mass M=2kg moves at a constant speed constrained by a string to move in a circle with radius .5m on a frictionless table. The tension in the string is 5N. What is the tangential speed? What is the angular velocity? What is the angular acceleration? How much work...

Homework Statement So I worked out a problem where a uniform disk with 3 forces being applied. I found the correct net torque acting on the disk. Now the problem is asking me to find the angular acceleration. Homework Equations r= I*(ang.acc^)2 The Attempt at a Solution I made...

Homework Statement Two square reflectors, each 1.00 cm on a side and of mass 4.00 g, are located at opposite ends of a thin, extremely light, 1.00-m rod that can rotate without friction and in a vacuum about an axle perpendicular to it through its center (the figure ). These reflectors are...

Homework Statement A large 16.0 kg roll of paper with radius R=18.0 cm rests against the wall and is held in place by a bracket attached to a rod through the center of the roll. The rod turns without friction in the bracket, and the moment of inertia of the paper and rod about the axis is...

Homework Statement A rigid rod of mass 3.50 kg and length of 2.70 m rotates in a vertical (x,y) plane about a frictionless pivot through its center. Particles m1 (mass=4.70 kg) and m2 (mass=2.60 kg) are attached at the ends of the rod. Determine the size of the angular acceleration of the...

Homework Statement http://imageshack.us/photo/my-images/855/10544781.png/ Homework Equations a=[r''-r0'^2]er+[r0'' + 2r'0']e0 where 0 = theta The Attempt at a Solution stumped about it, I've tried setting the above to 0 then work out r which is 200 m but that's just cluelessly...

Homework Statement A uniform horizontal rod of mass 2.3 kg and length 0.32 m is free to pivot about one end as shown. The moment of inertia of the rod about an axis perpendicular to the rod and through the center of mass is given by I = (ml^2)/12 If a 4.6 N force at an angle of 76 to...

I have no idea how to approach this problem. I'm not even sure if my visualization is right. Where do I start? Somebody please guide me; I'm not asking for a step by step solution to the answer. I just want to know how to do it. ________________________________________________ A thin...

I understand how the angular velocity was gotten, and why the amount of revolutions it took to travel 115 m was just 115/circumference of wheel. But why would radians need to be configured to find the angular acceleration? I thought angular acceleration was Δω/τ? And why is 2(thetasymbol) being...

Homework Statement An outdoor track is 420 ft. in diameter. A runner increases her speed at a constant rate from 14 to 24 ft./s over a distance of 95 ft. Determine the total acceleration of the runner 2 s after she begins to increase her speed.Homework Equations Vr = dr/dt Vθ = r*dθ/dt Ar =...

Homework Statement An Earth satellite moves in a circular orbit with an orbital speed of 6200 m/s. Find the time of one rotation as well as the radial acceleration of the satellite in orbit. Homework Equations Ac= V^2/R mAc=mg V= 2(pi)R/t The Attempt at a Solution Ok, I've...

Homework Statement A merry go round with a radius of 3 meters is at rest. The operator starts the merry go round up and it accelerates at a constant rate for 20 seconds. At the end of that time, the merry go round is moving at 10 revolutions per minute. 1) What was the angular acceleration of...

what does the direction of angular acceleration tell us ?

Homework Statement Calculate the angular acceleration and angular velocity of a 2kg object rotating in a circle of 1.5m radius in a time of 3s. Homework Equations w=v/r 2*pie*r The Attempt at a Solution Now i don't know how to fully work this out, not sure how to apply the...

Homework Statement angular acceleration of line a= -2w^2 rad/s when theta=pi/6, w= 10 rad/s what is angular velocity when theta= pi/3? Homework Equations chain rule The Attempt at a Solution w= e^-2theta is my answer, but I know this is wrong I know that this question is...

Homework Statement Hi, I have the following question and was wondering if anyone could help: A mass of 0.5kg is suspended from a flywheel, of mass 3kg, outside radius 0.3m and radius of gyration 0.212m. If the mass is release from rest and falls a distance of 0.5m in 1.5 seconds...

Homework Statement A cylinder with radius r = 0.6 m hangs in a horisontal frictionless axis. A string is winded around it and a constant force, F = 50.0 N, is acting on the string from t1 = 0 s to t2 = 2.00 s. During this time, L = 5 m of the string unwinds. The system starts from rest. a)...

Hey all! I'm currently doing some classical mechanics re-work and I've stumbled upon something that I don't quite understand. Calculating the angular velocity for, say a disc rolling on the ground, that has a tangential foce acting on it, I would view the angular acceleration from the middle...

Homework Statement Bars BC and AB and dish OA are attached by a pin like in the picture. The dish has a constant angular velocity \omega\_{0}. Find the angular acceleration of bars BC and AB. Homework Equations Relative Motion Equations: v_{b}=v_{A}+v_{A/B}...

Angular acceleration of a merry-go-round - no time given!? Homework Statement A merry-go-round accelerating uniformly from rest achieves its operating spped of 2.5rpm in 5rev. What is the magnitude of its angular acceleration? 2.5rpm=0.262rad/s Homework Equations angular...

Homework Statement http://img713.imageshack.us/img713/9151/screenshot20110501at113.png Homework Equations Angular acceleration = Torque/Inertia Torque = Fd Mass_moment_Inertia=mr^2 The Attempt at a Solution ->assume masses on the end of seesaw are point particles for calculating inertia. is...

This may be a weird one, so please hang in there with me on this. I have a large steel drum, its ~450kg. Measured to be 11.83kg/m^2 for its rotational inertia. (MOI). On the end of it we have a VERY accurate laser cut disk. Has 4 teeth, 4 gaps. Equally spaced and all the same "delay". When...

Homework Statement The cylinder is being pulled up the plane by a block. I've found that it IS rolling without slipping, and the acceleration is 5.00156 m/s^2. Homework Equations a=R[alpha] The Attempt at a Solution I've heard that the angular acceleration is the linear...

Homework Statement After some long calculations, I found that the linear acceleration of a cylinder on an inclined plane (attached to a block over a pulley on another inclined plane) was 8.76238 m/s^2. How do I find the angular acceleration of this rolling cylinder? Homework Equations...

Homework Statement Okay so this problem was in my test i did yesterday. While I finished it my teacher handed me the answers. Then i found his answer was half of mine for this question. But both answers seemed to be correct.. A projectile was launched from a trebuchet, the arm on the...

[b]1. A man sharpens a knife by pushing it against the rim of a grindstone. The 30-cm diameter stone is spinning at 200 rpm and has a mass of 28 kg. The coefficient of kinetic friction between the knife and the stone is 0.20. If the stone loses 10 % of its speed in 10s of grinding, what is the...

Homework Statement A computer disk drive is turned on starting from rest and has constant angular acceleration. If it took 0.640s for the drive to make its second complete revolution, how long did it take to make the first complete revolution? Homework Equations...

Homework Statement Homework Equations ? constant acceleration equations I guess The Attempt at a Solution They didn't get to this part in class today, yet it's expected on our online homework due tonight. No idea how to even get started.

Homework Statement Work out the moment about the axis of a disc with off-center hole when subjected to a linear acceleration. Homework Equations Parallel-axis theorem The Attempt at a Solution Moment of inertia of offset hole: I_oh=I_h+mr^2 where I_h is MoI of hole about its center...

I'm having some trouble converting mass to force in this problem. Any help would be appreciated. Homework Statement The pulley shown in the illustration has a radius of 2.70 m and a moment of inertia of 39.0 kg*m^2. The hanging mass is 4.20 kg and it exerts a force tangent to the edge of...

Homework Statement A curve of radius 54.7 m is banked so that a car of mass 2.4 Mg traveling with uniform speed 51 km/hr can round the curve without relying on friction to keep it from slipping on the surface.At what angle is the curve banked? The acceleration due to gravity is 9.8 m/s2 ...

Homework Statement A dentist’s drill starts from rest. After 3.07 s of constant angular acceleration, it turns at a rate of 24400 rev/min. Find the drill’s angular acceleration. Answer in units of rad/s2. Homework EquationsF=mv^2/r, vi=vf+at, a=v^2/r The Attempt at a...

Homework Statement Hello every one :) I do NOT understand rotational speed ect. SO A ball of mass 22.8 g is attached to a cord of length 0.739 m and rotates in a vertical circle. What is the minimum speed the ball must have at the top of the circle so the cord does not become slack? The...