Rotational motion Definition and 614 Threads

Homework Statement A thin, uniform 3.60kg bar has two balls glued on either end, each with a weight of 2.5kg. The length of the rod is 90cm and is balanced in the center. When one ball falls off calculate the angular acceleration just after this happens. (e.g the rod is falling in a...

Homework Statement A wheel starts from rest and accelerates uniformly to 200rpm in 6s. After it has been rotating for some time at this speed, the brakes are applied and it takes 5 minutes to stop the wheel. If the total number of revolutions is 3100, calculate the total time of rotation...

Homework Statement A mass-less rod of length, Ls, is rotating clockwise about a point, P1 in the horizontal plane. Attached by a cable of length, Ls, to the end of the rod and at angle θ is an object of mass, M. Starting at rest and then with the rod having and angular acceleration α, describe...

rotational motion and moment of inertia---HELP! Homework Statement Two masses m1=2.00 kg and m2=1.00 kg are linked by a thread and thrown over a pulley whose mass is 1.00 kg. The radius of the pulley is 0.200 m. a) Find the acceleration a with which the weights move b) the tensions T1...

Homework Statement A rotating bicycle wheel has an angular speed of 2.84 rad/s at some instant of time. It is then given an angular acceleration of 1.75 rad/s2. A chalk line drawn on the wheel is horizontal at t = 0. What angle does this line make with its original direction at t = 1.77 s...

Homework Statement A block slides down a frictionless half-pipe (shown on the back of this page). It is released from rest at the point (2,0). Determine the velocity, tangential accleration, radial acceleration and angular acceleration when the block goes through angular displacements of 30...

Its not actually a homework . i am just wondering . If we have 2 masses M and m where m rotates about M on either orbit1 of radius R with speed V or orbit 2 of radius r with seepd v , wouldn't its speed ratio V/v equal the following V/v = (sqrt(GM/R))/(sqrt(GM/r)) where G is gravitation...

Homework Statement Consider a small box of mass m sitting on a wedge with an angle θ and fixed to a spring with a spring constant k and a length in a non-stretched state L. The wedge rotates with an angular velocity ω around the vertical axis. Find the equilibrium position of the box...

Homework Statement 4. (9) On an old style record turntable a small rubber wheel is used to drive the larger platter. They are mounted so that their circular edges touch and do not slip while in motion. The small wheel has a radius of 2.0 cm and accelerates at the rate of 3.5 rad/s2 while it...

A thin spherical shell lying on a rough horizontal floor is hit by a cue in such a way that the line of action of force passes through the centre.so there is no torque and it moves with a linear velocity V and no angular velocity.the linear velo is to be founded when the shell starts purely...

A solid sphere of mass m is released from rest from the rim of a hemispherical cup so that it rolls along the surface. If the rim of the hemisphere is kept horizontal, find the normal force exerted by the cup on the ball when the ball reaches the bottom of the cup.

Two points are on a disk that rotates about an axis perpendicular to the plane of the disk at its center. Point B is 2.00 times as far from the axis as point A. If the linear speed of point is V, then the linear speed of point A is I know the speed of A must be less and i think its V/4. Is...

Two identical merry-go-rounds are rotating at the same speed. One is crowded with riding children; the other is nearly empty. If both merry-go-rounds cut off their motors at the same time and coast to a stop, slowed only by friction (which you can assume is the same for both merry-go-rounds)...

This isn't really a homework problem, more of a "I'm-building-something-and-need-to-make-sure-the-physics-are-right-before-I-build-something-impractical" problem. Homework Statement Homework Equations The Attempt at a Solution (I grouped it all together, easier for me to not separate each...

Homework Statement A puck, mass m, on the end of a (thin, light) string rotates in a circle of radius r_0 at a speed v_0 on a frictionless table. The radius of the circle is slowly reduced from its initial value by pulling the string through a hole in the table. A. Hence write down an...

Homework Statement A solid ball is released from rest and slides down a hillside that slopes downward at an angle 69.0 degrees from the horizontal. What minimum value must the coefficient of static friction between the hill and ball surfaces have for no slipping to occur? Homework Equations...

rotational motion, energy conservation problem URGENT please help Homework Statement A uniform rod of mass M=2 kg and length L = 2m is pivoted from its end. It has a point mass m=1 kg on its tip. It stars from rest at an angle of 30 degrees above horizontal. It falls under the influence of...

centripetal and tangential acceleration in rotational motion...? consider a stone attached to a string moving in a horizontal circle in a gravity field. now it has two accelerations one along the \hat{r} direction and the other along \theta\hat{} (theta hat) direction but there is only one...

Homework Statement Consider a bead of mass m that is confined to move on a circular hoop of radius r. The axis of symmetry of the hoop is horizontal, and the hoop is rotating about a vertical axis at a uniform rate \omega. Neglect friction and assume a constant gravitational acceleration of...

a) Two objects attract each other with a gravitational force of magnitude 9.30 x10-9 N when separated by 19.4 cm. If the total mass of the objects is 5.06 kg, what is the mass of each? Heavier mass_______kg Lighter mass______ kg my attempt: F=Gm1m2/r^2 so I rearranged to get m1 and m2...

Homework Statement A solid uniform marble and a block of ice, each with the same mass, start from rest at the same height H above the bottom of a hill and move down it. The marble rolls without slipping, but the ice slides without friction. Find the speed of each of these objects when it...

Homework Statement 9. A force can change angular rotational if it acts through: a. the axis of rotation *b. a lever arm tangential to the direction of rotation c. a moment arm parallel to the axis of rotation d. none of these Homework Equations n/a The Attempt at a...

Homework Statement 7. A 130-kg refrigerator that is 2.30 m tall and 90.0 cm wide is being delivered by a truck. The center of gravity of the refrigerator is located at its geometrical center and the refrigerator is facing sideways in the truck and is prevented from sliding. What is the...

Homework Statement 12. A motorcycle travels around a vertical 12 m radius loop. What is its speed at the top of the loop if the normal force exerted by the seat on the driver is equal to ¼ of his weight? a. 7 m/s b. 8.1 m/s *c. 9.4 m/s d. 15 m/s e. 88 m/s Homework Equations...

Homework Statement 11. A wheel with an angular speed of 2.0 rad/s is rolling on a horizontal surface and starts down a ramp. It rolls down the ramp with a constant angular acceleration of 2.5 rad/s2. If it takes 8 s to reach the bottom of the ramp, what is the final angular speed of the...

Homework Statement 9. A 0.61 kg mass attached to the end of a 0.50 m cord rotates in a vertical circle. The angular speed of the mass at the bottom of the circle is 2π rad/s. The tension in the string at this point is: a. 18 N b. 21 N c. 12 N *d. 54 N Homework Equations W=mg F=ma...

Homework Statement 3. A 1500 kg car is moving on an un-banked curve with a radius of 98 m. The coefficients of static and kinetic friction are 0.73 and 0.50 respectively. The maximum speed the car can move without skidding is: *a. 27 m/s b. 22.4m/s c. 21 m/s d. 30 m/s e. none...

Okay so my mechanics teacher is taking a rather mathematical approach to CM and its really confusing me. Can someone explain to me what this actually means? d hat{r}/dt=dot{theta} hat{theta} and d hat{theta}/dt=-dot{theta} hat{r} I mean I know that anything with a hat on top is a...

Homework Statement A marble is placed at the top of an inverted hemispherical bowl of radius R = 0.30 m. It starts from rest and slides down the bowl without friction. Draw a free body diagram when the marble reaches an angular position θ = 16.6°. From your FBD, sketch the approximate...

Homework Statement A student sits at rest on a piano stool that can rotate without friction. The moment of inertia of the student-stool system is 3.6 kg·m2. A second student tosses a 1.7 kg mass with a speed of 3.0 m/s to the student on the stool, who catches it at a distance of 0.38 m from...

Homework Statement Please see the attachment. Homework Equations The Attempt at a Solution Please see the attachment. When I tried to solve the equations for a I got a different answer and I don't see what I'm doing wrong. Please let me know if you cannot follow my work...

Homework Statement See attachment Homework Equations The Attempt at a Solution I'm confused as to why it's Ʃ F = m a = 20 + f as opposed to Ʃ F = m a = 20 - f Also when it states the net torque Ʃ torque = I alpha = ( 20 - f ) ( 0.10 ) = 0.02 ( a / 0.10 ) Why is...

A car is traveling around a horizontal circular track with radius r = 270 m at a constant speed v = 17 m/s as shown. The angle θA = 23° above the x axis, and the angle θB = 58° below the x axis. 1. What is the x component of the car’s acceleration when it is at point A? 2.What is the y...

Homework Statement See first attachment Homework Equations The Attempt at a Solution a = r * alpha r = a / alpha If I think of the whole pulley as a system... Ʃ F_sys = m_sys*a = Fg_1 - Fg_2 I called the 2 kg block, block 1, I called the 1.8 kg block block 2. a = [...

Homework Statement The question is given in the following pictures. http://imageshack.us/photo/my-images/851/iitjee2011.png/ http://imageshack.us/photo/my-images/844/iitjee20112.png/ This question had one or more than one correct answer(s). This was asked in IIT-JEE 2011 (which is...

Homework Statement A grindstone has a moment of inertia of 1.6*10^-3 kg m^2. When a constant torque is applied, the flywheel reaches an angular velocity of 1200 rev/min in 15 s. Assuming it started from rest, find (a.) the angular acceleration; (b.) the torque applied; (c.) the angle...

Can anybody please explain to me the concept of rotational motion?? I'm so lost in that chapter... ><

Homework Statement A 600 kg car is going around a banked curve with a radius of 110m at a speed of 24.5 m/s. What is the appropriate banking angle so that the car stays on its path without the assistance of friction? Homework Equations N cos{theta} = mg N sin{theta} = mv^2/r The...

They're both this? http://img37.imageshack.us/img37/4795/acccelerationrotational.jpg

I took physics in school, but our class kind of skipped over rotational motion, so I was just reading about it myself. I was wondering about whether rotating an object absorbed some of the energy put into it and, if so, how to calculate how much is transferred to the rotation.

Im looking over an example that was given in class that I jotted down in my notes; the question posed was...A 320 kg motorcycle includes two wheels each of which is 52 cm in diameter and has rotational inertia 2.1 kg*m^2. The cycle and its 75 kg rider are coasting at 85km/hr on a flat road when...

This a question that has been haunting me for some time now. Regarding the rotational motion of rigid bodies why wasn't the moment of inertia defined as the integral sum elements of infinitesimal mass time the radius from the axis of rotation rather than the radius squared. In this case the...

Im studying for a final, there are a few questions about rotational motion that i have, can anyone please help? A 5.2 kg disk of radius 2.3 m initially rotates about its axis at 6.4 rad/s. A tangential 7.4-N frictional force is applied to the rim of the disk. How many revolutions does the...

In uniform linear motion, an object moves at a constant speed v0. And as long as no acceleration is applied onto the object, it will continue move at the same speed and direction forever. For uniform circular motion to happen, an object must move at a constant speed v0 with a constant...

I'm sorry for posting another thread but I'm totally lost here.. Homework Statement A wheel and axle having a totel moment of inertia of 0.002kgm is caused to rotate about a horizontal axis by means of an 800g mass attached to a cord wrapped around the axle. The radius of the axle is 2cm...

Homework Statement A 20kg solid disk (I=1/2Mr^2) rolls on a horizontal surface at the rate of 4.0m/s Calculate its total kinetic energy The Attempt at a Solution I think that simply equating the KE to (0.5)(m)(v^2) would be a wrong solution because then I would not use the moment of...

Homework Statement A wheel starting from rest accelerates at 1.2 rad/s² counterclockwise. A) How long does it take to turn through 60 revolutions? B)What is the rotational speed at that time? 2. The attempt at a solution I converted 1.2rad/s² to 1.885 rev/s² by dividing by 2πrad (2...

Homework Statement A solid disk of mass 10 kg and radius 1 m is spinning around its central axis at a rate of ω = 20 rad/s. A force of magnitude 5 N is applied to the disk. Recall that the moment of inertia of a solid disk is I=(1/2)mr^2 . (a) Draw the disk and indicate the direction of...

In an inertia experiment using equipment very similar to the link below, I determined the following: Trial with two 100 g masses near the ends of the rotating apparatus (larger moment arm): - Final translational kinetic energy: 5.73 * 10^(-4) J - Final rotational kinetic energy: 0.638 J...

Homework Statement Can someone help me those 2 questions Homework Equations I don't understand how to convert to angular acceleration The Attempt at a Solution I attempted of finding the torque due to gravity then divided it by the radius for the second question, I got it wrong...