Physics Rotational Mechanics Level: High School
Moment of Inertia
Consider two uniform solid spheres where both have the same diameter , but one has the twice the mass of the other. The ratio of the larger moment of inertia to that of the smaller moment of inertia is ?6
8
4
2
10
Physics Rotational Mechanics Level: High School
Rotational Equilibrium
Suzee Cue , an intelligent physics student , needs to trim some tree branches which are extended out over the water . She invents the structure shown at “click here” to allow her to work at some distance from the end of a dock . She extends a 7.00 m long ,uniform board , having a mass of 100 kg , from the dock . On the dock end of the board , she has piled 250 . kg of sand . The center of gravity of the sand pile is 1.00 m inland from the end of the dock . Suzee has a mass of 50.0 kg .a) How far out over the water ,L , can Suzee work , before she gets wet . (ie , she and her apparatus tumble into the water) or can she work at the end of the board ?
b) If Suzee used this apparatus on Zarkon , would the limiting distance (L) be the same ? why or why not ?
Physics Rotational Mechanics Level: High School
Conservation of Energy
Consider the rotating platform of the above problem to be uniform disk of radius 2.50 m , with a total mass of 200.0 kg . The platform ultimately reaches a rotation rate of 5.00 rotations per second , at which point the acceleration stops and a 50.0 N force is applied to the rim of the platform by a brake mechanism which eventually brings the platform to a stop . The coefficient of kinetic friction between the brake pad and the platform is 0.800 .(Assume that the brake is the only cause of friction in the platform system and that the brake force is applied tangentially to the disk ) .a) What is the kinetic energy of the platform at its maximum rotation rate ?
b) What is the torque applied by the brake ?
c) How long does it take for the platform to stop rotating ?
Physics Rotational Mechanics Level: High School
Circular Motion
A box is sitting on a level rotating platform , 2.00 meters from the rotational axis of the platform . The coefficient of static friction between the box and the platform is 0.500 . An angular acceleration is applied to the platform . As the platform rotates faster and faster , the box will eventually slide off the platform .a) What is the speed of the box when it starts to slide ?
b) What is the rotation rate of the platform (in radians per second) when the box begins to slide ?
Physics Rotational Mechanics Level: High School
Rotational Equilibrium
Thee children are trying to balance on a seesaw , which consists of a fulcrum rock , acting as a pivot at the center , and a very light board 3.53 m long . Two boys are already on either end . The boy on the left has a mass of m1 = 43.0 kg , and the boy on the right has a mass of m2 = 36.5 kg . Where should the third child ,whose mass is m3 = 24.7 kg , place himself so as to balance the seesaw ? Distance are measured from the pivot with the positive direction to the right .a) -3.40 x 10^-1 m
b) 3.77 x 10^-1 m
c) -4.18 x 10^-1 m
d) 4.64 x 10^-1 m
e) -5.61 x 10^-1 m
Physics Rotational Mechanics Level: High School
Archimedes’s Principle
Five solid objects made of different material are placed in a tub of water .The objects are cubes made of wood . (SG = 0.5) , ice (SG = 0.92) , aluminum (SG = 2.7) ,steel (SG = 7.8) and gold (SG = 19.3) , All of the objects have the same mass . You hold the object on the bottom of the tub , Then you let the objects go .In the instant after release ,which of the following statements are true ?a) The aluminum cube would feel the least buoyant force .
b) The ice cube would move up with constant acceleration .
c) The ice cube would feel the greatest buoyant force .
d) The steel cube would displace the least water .
e) The would cube would displace its own volume in water .
Physics Rotational Mechanics Level: High School
In 1990 , a pizza of a radius 18.7 M was baked in South Africa , Suppose this placed on a rotating platform . If the pizza accelerated from rest to an angular velocity of 125 rad/sec in 25.0 s, what is the angular displacement of a point on the edge of the pizza during this time ?
Physics Rotational Mechanics Level: High School
Rotational Kinetics
A merry-go-round ,starting from rest , makes one complete rotation in 8.0 seconds before reaching its full speed , What is its angular acceleration ?a) 0.031 rad/s^2
b) 0.098 rad/s^2
c) 0.20 rad/s^2
d) 0.78 rad/s^2
e) 1.6 rad/s^2
Physics Rotational Mechanics Level: High School
Circular Motion
A car whose tires have radii of 50 cm travel at 36 km/h . What is the angular speed of the tires ?a) 5.0 rad/s
b) 10 rad/s
c) 20 rad/s
d) 72 rad/s
e) 200 rad/s
Physics Rotational Mechanics Level: High School
Mass m1 on a frictionless table is connected by a string through a hole in the table to a hanging mass m2 . With what speed must m1 rotate in a circle of radius r if m2 is to remain hanging at rest ?
Physics Rotational Mechanics Level: High School
A 500 g steel block rotates on a steel table while attached to a 2.0 –m-long massless rod . Compressed air fed through the rod is ejected from a nozzle on the back of the block , exerting a thrust force of 3.5 N . The nozzle is 70 degrees from the radial line . The block starts from rest . What is the blocks angular velocity after 10 revolutions ? What is the tension in the rod after 10 revolutions ?
Physics Rotational Mechanics Level: High School
A string is wrapped around a uniform solid cylinder of radius 2.30 cm. The cylinder can rotate freely about its axis . The loose end of the string is attached to a block . The block has mass 18.6 kg , and the cylinder has mass 12.6 kg .a) Find the magnitude infinite of the angular acceleration of the cylinder as the block descends .
b) What is the acceleration of the block ?
c) what is the tension in the string ?
Physics Rotational Mechanics Level: High School
Rotational Equilibrium
Two children sits on opposite direction ends of a light board of length 4 meters , pivoted about the middle . Child 1 has a mass of 20 kg and the Child 2 has mass 30 kg . The children are trying to balance the system with the board horizontal , by having only one of them move. Which child should move , and to what position , in order to balance the board ?
Physics Rotational Mechanics Level: High School
Circular Motion
An object moving in a circle of radius 2 meters moves through a 30 degrees arc . What distance does it travel along this arc ?
Physics Rotational Mechanics Level: High School
Circular Motion
A ball on the end of a string moves in a circle at a speed of 5 m/s , making one complete revolution in 2 seconds . What is the radius of the circle ?