Physics Rotational Mechanics Level: High School
Rotational Kinematics
The angular momentum of a spinning wheel is 234 kg m^2/s . After application of a constant braking torque for 2.0 s , it slows and has a new angular momentum of 111 kg m^2/m. What is the torque applied ?
Physics Rotational Mechanics Level: High School
Rotational Kinematics
A spinning flywheel has rotational inertial I = 401.4 kg*m^2 . Its angular velocity decreases from 20.4 rad/s to zero in 274.2 s due to friction . What is the frictional torque acting ?
Physics Rotational Mechanics Level: High School
Rotational Equilibrium
A rod is being used as a lever as shown . The fulcrum is 1.2 m from the load and 2.4 m from the applied force . If one load has a mass of 17.4 kg . What force must be applied to lift the load ?
Physics Rotational Mechanics Level: High School
Rotational Equilibrium
A house painter is standing on a uniform , horizontal platform that is held in equilibrium by two cables attached to supports on the roof . The painter has a mass of 77 kg and the mass of the platform is 20.5 kg. The distance from the left end of the platform to where the painter is standing is d = 2.0 m and the total length of the platform is 5.4 m .a) How large is the force exerted by the left-hand cable on the platform ?
b) How large is the force exerted by the right-hand cable ?
Physics Rotational Mechanics Level: High School
Rotational Kinetic Energy
A centrifuge has a rotational inertia of 5.4 x 10^3 kg m^2 . How much energy must be supplied to bring it from rest to 380 rad/s ?
Physics Rotational Mechanics Level: High School
Rotational Kinetic Energy
As a project your team is given the task of designing a spaceship of four different habitats . Each habitat is an enclosed sphere containing all necessary life support and laboratory facilities . The masses of these habitats are 10 x 105 kg , 20 x 105 kg , and 40 x 105 kg , and 40 x 105 kg . The entire station must spin so that the inhabitants will experience an artificial gravity . Your team has decided to arrange the habitats at corners of a square with 1.0 kg sides . The axis of rotation will be perpendicular to the plane of the square and through the center of mass . To help decide if this plan is practical ,you calculate how much energy would be necessary to set the space station spinning at 5.0 revolutions per minute . In your team’s design , the size of each habitat is small compared to the size of the space between the habitats and the structure that holds the habitats together is much less massive than any single habitat .
Physics Rotational Mechanics Level: High School
Centre of Mass
The figure shows (at “click here” ) , four point masses are placed as shown. The x-and y-coordinates of the center of mass are closest to :a) (2.2, 2.6)
b) (2.2, 2.7)
c) (2.3, 2.6)
d) (2.3, 2.7)
e) (2.3, 2.8)
Physics Rotational Mechanics Level: High School
Movement of Inertia
Consider a light rod of negligible mass and length L pivoted on a frictionless horizontal bearing at a point O . Attached to the end of the rod is a mass M1 . Also , a second mass M2 of equal size (ie, M1 = M2 = M) is attached to the rod (6/9 L from the lower end) , as shown in the figure at “click here” . What is the moment of inertia I about O ?1) I = 29/25 M L^2
2) I = 106/81 M L^2
3) I = 74/49 M L^2
4) I = 53/49 M L^2
5) I = 17/16 M L^2
6) I = 10/9 M L^2
A) What is the period of this pendulum in the small angle approximation ?
Physics Rotational Mechanics Level: High School
Conservation of Energy
Two physics students , Joe and Willie , decided to fling balloons filled with M1 = 71.9 grams of ice water at coeds who are sun bathing on the roof of a sorority house two blocks east of the physics building at UC Berkeley . Joe and Willie built a trebuchet on the roof of the physics building . For the large mass , M2, they cast a solid lead sphere D2 = 24.2 cm in diameter . M1 was mounted so that its center of mass is at a distance L1 = 4.46 m from the axis of rotation and M2 was mounted so that its center of mass was L2 = 0.26 m from the axis of rotation. Assume that the trebuchet is loaded in the horizontal position and that the balloon leaves the arm at the highest point of rotation. Ignore friction, the moments of inertia of the arms, etc .a) Calculate the mass of the load sphere .
b) Calculate maximum angular velocity achieved by the trebuchet .
c) Calculate the tangential velocity with which the balloon begins its flight
Physics Rotational Mechanics Level: High School
Circular Motion
Atilla (mass M1 = 3.99 kg ) has fallen into a well . A freak earthquake has set the water in the well spinning (W1 = 3.99 Rad/sec) about a vertical axis thus carrying Attila around and around . The radius of the well is R1 = 17.1 cm . Calculate Atilla’s centripetal acceleration . Ac, the centripetal force on Atilla Fc, and Atilla’s Tangential Velocity , Vt.
Physics Rotational Mechanics Level: High School
Rotational Kinematics
The turntable of a record player rotates initially at 30 rev/min and takes 10 s to come to rest .a) What is the angular acceleration of the turntable ?
b) How many rotations does the turntable make before coming to rest ?
c) If the radius of the turntable is 0.20 m , what is the initial linear speed of a bug riding on the rim ?
Physics Rotational Mechanics Level: High School
Conservation of Angular Momentum
Two disks are mounted (like a merry-go-round ) on low friction bearings on the same axle and can be brought together so that they couple and rotate as one unit . The first disk, with rotational inertia 3.30 kg m^2 about its central axis , is set spinning counterclockwise at 450 rev/min . They then couple togethera) What is their angular speed after coupling ? If instead the second disk is set spinning clockwise at 900 rev/min ,
b) what are their angular speed
c) the direction of rotation after they couple together ?
Physics Rotational Mechanics Level: High School
Loop The Loop
In the figure which is shown at “click here“ , a solid brass ball of mass 0.280 g will roll smoothly along a loop-the-loop track when released from rest along the straight section the circular loop has radius R = 14.0 cm , and the ball has radius r<b) magnitude and
c) direction of the horizontal force component acting on the ball at point Q ?
Physics Rotational Mechanics Level: High School
Pulley with rotational Inertia
In the figure which is shown at “click here” two blocks, of mass m1 = 400 g and m2 = 600 g , are connected by a massless cord that is wrapped around a uniform disk of mass M = 500 g and radius R = 12.0 cm . The disk can rotate without friction about a fixed horizontal axis through its center ; the cord cannot slip on the disk . The system is released from rest . Find .a) the magnitude of the acceleration of the blocks
b) the tension T1 in the cord at the left
c) the tension T2 iu the cord at the right
Physics Rotational Mechanics Level: High School
Pulley with rotational Inertia
In the figure which is shown at ‘click here’ two 6.20 kg blocks are connected by a massless string over a pulley of radius 2.40 cm and rotational inertia 7.40 x 10^-4 kg m^2 . the string does not slip on the pulley , it is not known whether there is friction between the table and the sliding block; the pulleys axis is frictionless. When this system is released from rest , the pulley turns through 1.30 rad in 91.0 ms and the acceleration of the block is constant . What area) the magnitude of the pulley’s angular acceleration
b) the magnitude of either blocks acceleration
c) string tension T1
d) string tension T2
