What is Rotational motion: Definition and 610 Discussions
A rotation is a circular movement of an object around a center (or point) of rotation. The geometric plane along which the rotation occurs is called the rotation plane, and the imaginary line extending from the center and perpendicular to the rotation plane is called the rotation axis ( AK-seez). A three-dimensional object can always be rotated about an infinite number of rotation axes.
If the rotation axis passes internally through the body's own center of mass, then the body is said to be autorotating or spinning, and the surface intersection of the axis can be called a pole. A rotation around a completely external axis, e.g. the planet Earth around the Sun, is called revolving or orbiting, typically when it is produced by gravity, and the ends of the rotation axis can be called the orbital poles.
Homework Statement
A supernova is the explosion of a large star. The progenitor, the star just before it explodes has a mass of 15 solar masses and a radius of 7*10^10m. After the supernova, a pulsar is left over. The pulsar has a mass of 2.2 solar masses and a radius of 10km.
a) If the...
Kinetic Energy rotational motion problem, help please!
Homework Statement
A 2.4 kg cylinder (radius = 0.11 m, length = 0.50 m) is released from rest at the top of a ramp and allowed to roll without slipping. The ramp is 0.62 m high and 5.0 m long.
(a) When the cylinder reaches the...
Homework Statement
A rigid body is rotating about a fixed axis through the origin. The angular velocity is \omega\hat{k} where \omega is positive. What is the unit vector in the direction of the velocity of a point on the body located on the positive y axis?
The Attempt at a...
3 Questions about Rotational Motion; Test Tomorrow! Please Help!
Problem 1
Homework Statement
A uniform disk of radius .12m and mass 5kg is pivoted so that it rotates freely about its axis. A string wrapped around the disk is pulled with a force of 20N.
a. What is the torque exerted on...
Homework Statement
A yo-yo is made from two uniform disks of raduis R with a combined mass of m. A short massless shaft of radius r connects the disks. A long thin string is wrapped around the shaft several times by a yo-yo player, who releases it with zero speed. Assuming that the string is...
Homework Statement
A uniform disk turns at 9.5 rev/s around a frictionless spindle. A nonrotating rod, of the same mass as the disk and length equal to the disk's diameter, is dropped onto the freely spinning disk, see the figure. They then turn together around the spindle with their centers...
Homework Statement
When the wheels of a landing airliner tough the runway, they are not rotating initially. The wheels first slide on the runway (and produc eclouds of smoke and burn marks on the runway, which you may have noticed), until the sliding friction force has accelerated the wheels to...
A pendulum bob is released from some initial height such that the speed of the bob at the bottom of the swing is 3.0 m/s. What is the initial height of the bob?
I am not asking to do the problem for me, I am just unsure how to approach this problem. I am just looking for what i need to...
In Figure 11-32, a solid brass ball of mass m and radius r will roll without slipping along the loop-the-loop track when released from rest along the straight section. For the following answers use g for the acceleration due to gravity, and m, r, and R, as appropriate, where all quantities are...
Homework Statement
thin, hollow 60.0 g section of pipe of radius 14.0 cm starts rolling (from rest) down a 17.5° incline 5.60 m long.
(a) If the pipe rolls without slipping, what will be its speed at the base of the incline?
(b) What will be its total kinetic energy at the base of the...
Homework Statement
A uniform, spherical bowling ball of mass m and radius R is projected horizontally along the
floor at an initial velocity v0 = 6.00 m/s. The ball is not rotating initially, so w0 = 0. It
picks up rotation due to (kinetic) friction as it initially slips along the floor...
Homework Statement
A 4.00 kg mass and a 3.00 kg mass are attached to opposite ends of a thin 44 cm long horizontal rod (see figure). The system is rotating at angular speed ω = 6 rad/s about a vertical axle at the center of the rod.
(a) Determine the kinetic energy K of the system.
(b)...
Consider a free floating spacecraft in space sufficiently far from any gravitational or other external forces. The spacecraft is equipped with attitude control thrusters. The thrusters fail and fire randomly and intermittently but symmetrically about the craft's centre of mass i.e. the craft...
A rotating water pump works by taking water in at one side of a rotating wheel, and expelling it from the other side. If a pump with a radius of 0.120 m starts from rest and accelerates at 35.0 rad/s2, how fast will the water be traveling when it leaves the pump after it has been accelerating...
At least, they're difficult for me. I find them very hard to set up, in particular the interaction of the rotation and translation is hard for me to grasp. I've worked on both of these very hard, with only some headway, so be liberal in your help.
(For some reason, all my greek letters are...
Homework Statement
A disk with a mass of 4kg and a .20m radius is free to rotate about a horizontal axis. A 4.0kg mass and a 8.0kg mass are attached by a massless string, which is hung over the disk. If the string does not slip, what is the angular velocity of the disk after 2 seconds...
1. There is a figure showing two thin beams joined at right angles. The vertical beam is 15.0 kg and 1.00m long and the horizontal beam is 25.0 kg and 2.00m long.
Part a) askes to find the center of gravity to the two joined beams, taking the origin at the corner where the beams join...
Homework Statement
A rubber ball with a radius of .048 m rolls along the horizontal surface of a table with a constant linear speed v. When the ball rolls off the edge of the table, it falls 0.85 m to the floor below. If the ball completes 0.82 revolutions during its fall, what was its linear...
Homework Statement
A wheel with 16 spokes rotating in the clockwise direction is photographed on film. The film is passed through a projector at the rate of 24 frames/s, which is the proper rate for the projector. On the screen , however, the wheel appears to rotate counterclockwise at 4.0...
Homework Statement
A computer hard disk starts from rest, then speeds up with an angular acceleration of 198 rad/s2 until it reaches its final angular speed of 7683 rpm. How many revolutions has the disk made 10.7 s after it starts up?
Homework Equations
t=wf/a
delta0=wi*t+(1/2)(a)t^2...
Homework Statement
A car starts from rest and moves around a circular, horizontal, level track of radius 30 m. Its speed increases at the constant rate of 0.5 m/s^2. (a) What is the magnitude of the net acceleration 15 s later? (b) What angle does the net acceleration make with the car's...
In my physics class one of the problems we have been given to solve is:
"A small button placed on a horizontal rotating platform with diameter 0.330m will revolve with the platform when it is brought up to a rotational speed of 44.0 rev/min, provided the button is a distance no more than...
A rigid body is made of three identical thin rods, each with length L=0.60m, fastened together together in the form of a letter H. The body is free to rotate about a horizontal axis that runs along the length of one of the legs of H. The body is allowed to fall from rest from a position in which...
Homework Statement
A rock of mass m=2kg is tied to a string of length r=4m is rotating at a constant rate and subject to a centripetal force Fc=32N.
Find the:
a)Centripetal acceleration
b)Angular velocity
c)Angular momentum
Homework Equations
a) Ac=V2T/R (Fc=V2T/R; so...
I have a test Monday and I'm trying some review problems my professor gave us to study from. I'm not looking for answers I'm just looking for someone to help step me through a few of these problems. Thanks for any and all help you guys can provide.
Homework Statement
3a). After starting...
Homework Statement
A hollow cylinder (hoop) is rolling on a horizontal surface at speed v=3.3m/s when it reaches a 15 degree incline. How far up the incline will it go? How long will it be on the incline before it arrives back at the bottom.
Homework Equations
SOH CAH TOA
MGH=KEtrans...
You stand on the edge of a large rotating disc. It rotates at a constant speed. You walk towards the centre of the disc. What do you experience?
radius is decreasing, therefore inertia and linear velocity are decreasing.
but angular acceleration will increase.
i don't know if I'm right
Homework Statement
A yoyo is made of two solid cylindrical disks each of mass .050kg and diameter .075m joined by a concentric thin solid cylindrical hub of mass .0050kg and diameter .010m. use conservation of energy to calculate the linear speed of the yoyo when it reaches the end of its 1...
Homework Statement
A long thin tube of negligible mass is pivoted so it may rotate freely without friction in a horizontal plane. A thin rod of mass M and length L lies in the tube and can slide without friction in the tube. (I_{Thin Rod}=\frac{1}{12}ML^{2}).
Find the equations of motion...
Homework Statement
A disk (yo-yo) of Radius R and mass m is attached to a weightless cord on the disk's edge. At time zero, the disk is released and a force upwards is applied to the upper end of the chord so that the center of mass of the disk does not move up or down. What must be the minimum...
Homework Statement
A tire placed on a balancing machine in a service station starts from rest and turns through 4.9 revolutions in 1.0 s before reaching its final angular speed. Calculate its angular acceleration.
I need my answer in
rad/s^2
Homework Equations
a=w/t
1rev= 2n rad...
heres the problem I am working on
http://img55.imageshack.us/img55/8568/urgei5.jpg
I got the first part but I can't get the correct answer to how many revolutions the rotor executes before coming to rest...
I tried using the kinematic equations but can't come up with 27,900...
Heres the problem I am workin on
http://img294.imageshack.us/img294/9166/rotatesm3.jpg
Now in order to find the magnitude of accleration I am assuming I would need to find the two components of acceleration first, Centripetal and Tangential...
I found tangetial by the formula
a_{t}...
I'm studying the chapter on rotational motion, and I have a problem that I don't have a clue how to solve, the problem is this: A spool of wire of mass M and radius R is unwound under a constant force F. (F is parallel to the ground) Assuming the spool is a uniform solid cylinder that doesn't...
Homework Statement
A uniform solid sphere, with diameter 28 cm and mass 2.5 kg, rolls without slipping on a horizontal surface, at constant speed of 2.0 m/s.
1) What is the rotational kinetic energy?
2) What is its total kinetic energy?
3) What is its angular momentum?
Homework...
I understand that the Sun's gravity force provides the centripetal force for the Earth to orbit around it. However, what provides the torque for the rotational motion of Earth?
[SOLVED] Energy in Rotational Motion
There is a clock that has an hour hand 2.7m long with a mass of 60 kg. The minute hand is 4.5m log with a mass of 100 kg. What is the total rotational kinetic energy assuming the hands act as long thin rods?
K=I*rotation vel.^2
I=(1/3) ML^2 ( I think...
let's say a wheel rotates with a constant angular acceleration. Would its angular speed be affected if the radius was changed? It seems that angular speed would be independent of the radius since the angle is just a proportional quantity.
hi everybody!I am to find the direction in which friction acts in rotational moton. In some cases we say friction supports rotational motion and in some others we say it doesn't.Plz help me to sort it out
thanks
I'm in my first semester of Physics and i am having trouble understanding UCM, RM, Torque, and Inertia. The few things i do understand is Torque=rF(perpendicular)sin(theta) and that all points on a rigid rotating body have the same angular acceleration. please can someone help me?
Homework Statement
A wheel of diameter of .68m roll without slipping. A point at the top of the wheel moves witha tangential speed of 5.4m/s. Whaat speed is the axle of the wheel moving? What is the angular speed of the wheel?
How would i approach to do this problem, what equations would...
A wheel of diameter of .68m roll without slipping. A point at the top of the wheel moves witha tangential speed of 5.4m/s. Whaat speed is the axle of the wheel moving? What is the angular speed of the wheel?
Can someone work this problem out, so i can see how its done. My teacher flies...
A ballerian spins initially at 1.5rev/s when arms are extended. She then draws in her arms to her body and her moment of intertia is .88kg m^2 and her angular speed increases to 4.0rev/s. Determine the network she did to increase her angular speed?
So i first needed to solve for the initial...
Homework Statement
How fast (in rpm) must a centrifuge rotate if a particle 7.0 cm from the axis of rotation is to experience an acceleration of 100,000 g's?
My variables
radius= 7 cm or .07m
radial accel= 100,000 g's or 980,000m/s^2 or 98,000,000cm/s^2
V= I think I need this to get w...
Homework Statement
A 4-kg mass is attached to a vertical rod by two strings as in the figure shown. The strings are under tension when the rod rotates about it's axis. If the speed of the mass is a constant 6 m/s in the horizontal plane, find the tension in the upper and lower strings. DRAW...
Homework Statement
A stepladder of negligible weight is constructed as shown. A painter of mass 70 kg stands on the ladder 3 meters from the bottom. Assuming that the floor is frictionless, find (a) the tnesion in the horizontal bar connecting the two halves of hte ladder, (b) the normal...
hello all, I'm studying from my midterm and having some trouble figuring out the question below..thanks for the help
A uniform ladder of length L and mass m1 rests against a frictionless wall. the ladder makes an angle "theta" with the horizontal.
a) find horizontal and vertical forces...
[SOLVED] Rotational Motion question!
Homework Statement
A wheel has a radius of 2.8 m. How far does a point on the circumference travel if the wheel is rotated through angles of 30 degrees, 30 radians, and 30 revolutions?
Homework Equations
The Attempt at a Solution
I tried to...
1.
Problem Statement
What is the chance of a light car safely rounding an unbanked frictionless curve compared to a heavy car? Both cars have the same speed and tires.
Solution
I know that tan(theta)=v^2/(rg) proves that weight does not matter but I do not understand why and my book doesn't...
[SOLVED] Rotational Motion
Homework Statement
Four small spheres, each of which you can regard as a point of mass m = 0.170 kg, are arranged in a square d = 0.250 m on a side and connected by light rods (Fig. 9.27).
(a) Find the moment of inertia of the system about an axis through the...