What is Rotational: Definition and 1000 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.
Hi,
I was wondering if the formula for rotational energy:
E = 1/2 * L * w
where L is the angular momentum and w is the angular velocity,
is actually correct for relativistic velocities.
Using
L = p * r
and
w = v / r
where
p = the linear momentum = m * v
We get...
Homework Statement
http://apcentral.collegeboard.com/apc/public/repository/ap04_frq_physics_cm_36191.pdf
The problem can be found here. I am stuck on problem 2 d.
Homework Equations
I = m(g-a)R2 / a //found in part c
The Attempt at a Solution
I don't understand why the...
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
A solid sphere with a mass 8.2kg and radius 10cm is sliding along a frictionless surface with a speed 5.4m/s while at the same time spinning. The sphere has 0.31 of its total kinetic energy in translational motion. How fast is the sphere spinning?
Homework Equations...
Hi
I am analysing some piping which starts off as being aligned with the global axis system (X Y Z). So axially its X, laterally is Y and Z is vertically upwards. Due to bends etc. the end of the pipe is in a different orientation though still in the same plane - now the local axis system is x...
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...
A small, solid, uniform ball is to be shot up from point P so it rolls smoothly along a horizontal path, up along a ramp, and onto a plateau. Then it leaves the plateau horizontally to land on a game board, at a horizontal distance (d=6cm) from the right edge of the plateau. The vertical...
The Problem:
A thin rod of mass 0.490 kg and length 1.16 m is at rest, hanging vertically from a strong, fixed hinge at its top end. Suddenly, a horizontal impulsive force (12.7) N is applied to it.
a) Suppose the force acts at the bottom end of the rod. Find the acceleration of its center...
Homework Statement
There is a system consisting of two masses, m1=20 kg, m2=30kg on a pulley and m2 is 2 meters above the ground, while m1 is on the ground.
This is the question: the system released from rest a 30 kg block that is 2m above a ledge. The pulley is a disk with radius of 10 cm...
In Figure, block 1 has mass m1 = 430 g, block 2 has mass m2 = 540 g, and the pulley is on a frictionless horizontal axle and has radius R = 5.3 cm. When released from rest, block 2 falls 80 cm in 5.3 s (without the cord slipping on the pulley). What is the pulley's rotational inertia? Caution...
A cord is wrapped around the rim of a solid uniform wheel 0.240m in radius and of mass 8.80kg. A steady horizontal pull of 30.0N to the right is exerted on the cord, pulling it off tangentially from the wheel. The wheel is mounted on frictionless bearings on a horizontal axle through its center...
Listed below are just a things I cannot figure out involving rotational motion (one involves a situation).
-Why does Kinetic Friction do no work if bodies roll without slipping? I thought it would add torque to provide more energy for rotational motion.
Situation: A solid bowling ball...
Homework Statement
A uniform solid sphere rolls on a horizontal surface at 20m.s^-1 and then rolls up an incline which has an angle on inclination of 30°. Ignoring friction, calculate the height attained by the sphere.
Homework Equations
Weren't given any specific equations to work...
Say you have a convex 2D polygon with a set of vertices rotating on a flat surface. Given the coefficient of friction and the coordinates of each vertex, how can you determine the torque from friction on this polygon? I'm looking more for an algorithm than some big equation, as this is something...
Homework Statement
The system is balancing rod on its tip. The coordinate system is polar, and the problem is one dimensional with angle \theta . Only forcee on this rod is gravitational force. The problem is finding potential in therms of moment of inertia I. My question is it possible to...
Homework Statement
Two blocks A and B are attached to a spring of force constant K and are placed on a horizontal surface. The coefficient of friction between block A and surface is zero while between block B and surface is μ. A spherical ball of mass M, radius R impinges on block A with...
Hi guys,
I need to model a ball rolling on an incline plane, and i would like to be able to calculate acceleration due to gravity for a given angle.
Currently i have:
a = f / m
f = m*g*sin(angle)
a = g*sin(angle)
I am aware this does not take rotational motion into account, which is what...
Homework Statement
The four particles shown below are connected by rigid rods of negligible mass where y1 = 6.60 m. The origin is at the center of the rectangle. The system rotates in the xy plane about the z axis with an angular speed of 5.40 rad/s...
A car is moving foreword with a constant acceleration. I know the point of the tire in contact with the ground has a velocity of 0 (relative to the ground). Is the tangential acceleration at this point also zero? I came across an example problem in my text where this occurs and and it does not...
Homework Statement
Starting from rest, a basketball rolls from the top of a hill to the bottom, reaching a translational speed of 6.12 m/s. Ignore frictional losses.
Homework Equations
(a) What is the height of the hill?
(b) Released from rest at the same height, a can of frozen...
Homework Statement
A small compass needle is situated in a uniform magnetic field. When displaced from its stable equilibrium position through a small angle and then released, it oscillates with a frequency of 5 Hz. A millijoule of work is needed to twist the compass needle round through...
Homework Statement
A slender rod shown in the figure has a mass m and length l and is released from rest when theta=0 degrees. The horizontal and vertical components of force which the pin at A exerts on the rod at the instant shown in the figure is ?
The Attempt at a Solution
I have some...
Homework Statement
Show that the rotational wavefunction 3cos2? -1 is an eigenfunction of the
Hamiltonian for a three dimensional rigid rotor. Determine the corresponding eigenvalue.
Homework Equations
the eigenstates are |l,m>
the quantum number of the total angular momentum is l...
Homework Statement
A thin uniform-density rod whose mass is 3.8 kg and whose length is 3.0 m rotates around an axis perpendicular to the rod, with angular speed 34 radians/s. Its center moves with a speed of 10 m/s.
(a) What is its rotational kinetic energy?
(b) What is its total kinetic...
Hi everyone!
I wanted to know if there is a possible way for a human-being to create a rotational motion of
water in a metallic box by himself, probably using his own electric field (is there such a thing?)
with no other accessories? It might be related to the term "Electric people"...
Rotational mechanics...
Homework Statement
This is actually a simple harmonic motion question but the doubt i have is with a concept in rotation...
I will state the exact problem...
A solid sphere(radius R) rolls without slipping in a cylindrical trough(Radius 5R).
Find the time period of...
I've just watched this vid about rotations and torque:
http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/lecture-21/
and they say that if u hit or pull something for a corner for example.. it will have the same speed like if u hit it in center...
Homework Statement
A spherical body is rolling on a rough surface.
then "the frictional force may or may not be zero"
Is this statement is correct or not?
we discussed about this in classroom.
Some were saying it must not be zero and others were saying it may be zero.
Which is correct?
Hey I'm making some kind of simulation... (in game maker) Ball collisions, ball to wall(friction)etc.
So I'm asking: how do i calculate rotational speed if i know r, mass, and distance to where is force being applyed?
I know that moment of inertia for a ball is 2/3*m*r2 and have no idea...
See the attached PDF document, all information is given and the help I need is on number 2-5, which is all one problem. I do already know that you have to do 2, then 5, then 3, then 4. Between 30 of my friends and I, we cannot get it.
Thanks in advance.
Hi all; I'm building a mechanism that will raise and lower a small platform but I need to determine how much force is needed. Sadly, until the platform is built and set up I won't know how heavy it will be so I'm trying to just determine how to calculate the force various motors can put out so I...
Homework Statement
There is a record spinning when a blob of putty falls vertically on its edge; which is .10m from the center. What is the rotational speed of the record after the blob sticks on it?
additional information:
mass of blob = .040kg
mass of record = .10kg
rotational inertia of...
Rotational Accel/Radians <<Solved>>
Homework Statement
Question 1)
18. Convert the following measurements to radians.
c) the motion of an hour hand in 4.4 h = 2.3 Rad
d) Earth’s rotation in 28.5 h = 7.5 Rad
<<<<<<figured it out, thanks SammyS for that obivious yet overlooked detail...
Homework Statement
Estimate the total rotational moment of inertia in Kg*m^2, of all the motors and generators in the Eastern United States.
Homework Equations
No other information was provided.
The Attempt at a Solution
First off I went to the following website to estimate the...
Homework Statement
What is the rotational kinetic energy of Jupiter? Assume Jupiter is a uniform sphere with a rotational period of 9.81 hr.
Homework Equations
I= 2mr^2/5
Krot= I*omega^2/2
omega= 2pi/T
The Attempt at a Solution
i found the omega using the equation above and the...
Technically this is a homework question because it's from an assignment I'm doing as practice for my exam tomorrow.
Imagine a rod standing on a table, the base of the rod is attached to the table with a hinge, so that the rod is able to swing between standing position and parallel with the...
Homework Statement
Two rings of masses 'm' (smaller one) and '4m' (bigger one) are placed in the set up as shown in the diagram. The smaller ring is hung through a horizontal frictionless thread. The bigger ring is joined to the smaller ring in such a way that it can rotate freely about the...
Homework Statement
Two rings of masses 'm' (smaller one) and '4m' (bigger one) are placed in the set up as shown in the diagram. The smaller ring is hung through a horizontal frictionless thread. The bigger ring is joined to the smaller ring in such a way that it can rotate freely about the...
Homework Statement
An inelastic uniform sphere of radius 'a' is sliding without rotation on a smooth horizontal plane when it impinges on a thin horizontal rod at right angles to its direction of motion and at a height 'b' from the plane. Find the maximum velocity so that it will just roll...
1. A space station in the form of a large wheel, 124 m in diamete, rotates to provide and "artificial gravity" of 9.3 m/s^2 for people located on the outer rim.
Find the rotational frequency of the wheel that will produce this effect.
(answer in units of rpm)
2. v^2=gr, w=v/r, w/2pi =...
In a class demonstration, a bicycle wheel was held on an axle and spun. The result came to be that the wheel while rotating held a vertical position while holding it by a string attached to the end of the axle. After the wheel stopped rotating its vertical position ceased and the wheel attained...
Homework Statement
The figure shows a view from above of two objects attached to the end of a rigid massless rod at rest on a frictionless table. Imagine a vertical rod, on the top end is a mass of m, an the bottom is a mass of 2m. The length of the rod is L and L/4 down from m (at top), a...
MMX proves light is isotropic in all directions.
Hand held GPS units apply the Earth rotational sagnac correction which means light is not isotropic in all directions at the unit from the satellites.
If a hand held GPS unit is placed at the same location as an MMX experiment, one...
I need some help with physics...Honestly, I'm a bit slow in the class and it's killing my GPA
How do I calculate torque and normal force?
I'm working on a lab. Basically, I'm balancing a meter stick with two different mass on both sides sides with a fulcrum in between them. I need to...
we have many accelerations in rotational motion ,and I don't know the difference between them. first the linear acceleration which as I understand is the vector acceleration which has the same direction as the change of velocity and it affects the speed and direction then it's two components are...
Homework Statement
This is a question from the 1999 AP Physics C test.
You can view the picture here, on Page 6:
http://vhphysics.com/ap/x-test-q/Resource/b)%20Physics%20C%20Materials%20(656)/c)%20AP%20C%20Free-Response%20Problems%20(213)/Physics%20C%201999%20Free%20Response.PDF
As...
Im doing a study on a polyatomic molecule which is assigned by six quantum numbers, namely the three vibrational modes, and the Rotational quantum number J, and its projections on the A and C axes, (Ka and Kc):
J, Ka, Kc, v1, v2, v3
Each combination of these numbers has an energy in...
Homework Statement
Two spherical bodies with equal mass m1=m2=1000 kg are orbiting around a common barycenter in a weightless environment because of the gravitational attraction.
A: Show how the frequency of orbiting is related to the distance between two bodies.
B: We connect two...