Physics Rotational Mechanics Level: High School
Equations of Rotational Motion
A gymnast is performing a floor routine . In a tumbling run she spins through the air , increasing her angular velocity from 3.00 to 5.45 rev/s while rotating through one-half of a revolution, How much time does this maneuver take ?
Physics Rotational Mechanics Level: High School
A pulsar is a rapidly rotating neutron star that continuously emits a beam of radio waves in searchlight manner . Each time the pulsar makes one revolution, the rotating beam sweeps across the earth , and the earth receives a pulse of radio waves . For one particular pulsar , the time between two successive pulses is 0.076 s . Determine the average angular speed (in rad/s) of this pulsar .
Physics Rotational Mechanics Level: High School
Centre of Mass
Dicardo, mass 80 kg , and Carmelita are enjoying Lake Merced at dusk in a 30 kg canoe . When the canoe is at rest in the placid after they change seats , which are 3 meters apart and symmetrically located with respect to the canoe’s center . Ricardo notices that the canoe moved 0.4 m relative to a submerged log , and calculates Carmelita’s mass , which she has declined to tell him . What is it ?
Physics Rotational Mechanics Level: High School
Torque
To tighten a bolt , you push with a force of 80 Newton’s at the end of a wrench handle that is 0.25 meters from the axis of the bolt .a) What torque are you exerting ?
b) If you move your hand inward to be only 0.10 meters from the bolt , what force do you have to exert to achieve the same torque ?
c) Do your answers depend on the direction of you push relative to the direction of the wrench handle ?
Physics Rotational Mechanics Level: High School
What is gyroscope and how is it used as a navigational aid ?
Physics Rotational Mechanics Level: High School
Conservation of Angular Momentum
a)Explain how skates can quickly go from a slow to fast spin and vice versa .b) What happens to their angular velocity and moment of inertia ?
c) Is an external torque required ? Explain .
Physics Rotational Mechanics Level: High School
Rotational Inertia
In terms of rotational inertia , explain why :a) It’s hard to walk without bending your knees .
b) Short-legged people step more quickly than long-legged people do :
c) You can swing a baseball bar faster than a long one of the same weight .
Physics Rotational Mechanics Level: High School
Circular Motion
A bicycle has wheels with a 30-centimeter radius . If smaller wheels with a 25-centimeter radius are installed , what is the change in linear speed of the bicycle if the wheels rotate at 1 revolution per second ?
Physics Rotational Mechanics Level: High School
Explain the difference between linear speed and rotational speed . Include formula difference and how rotational speed is changed to linear speed .
Physics Rotational Mechanics Level: High School
Rotational Kinetic Energy
(a) Calculate the kinetic energy that the earth has because of its rotation about its own axis , Assume that the earth is a uniform sphere and that its path around the sun is circular . For comparison, the total energy used in the United States in one year is about 9.33 x 10^9 J .(b) Calculate the kinetic energy that the earth has because of its motion around the sun .
Physics Rotational Mechanics Level: High School
Rotational equilibrium
A lunch tray is being in one hand , as the drawing illustrates . The mass of the tray itself is 0.120 kg , and its center of gravity is located at its geometrical center . On the tray is a 1.00 kg plate of food and a 0.215 kg cup of coffee . Obtain the force T exerted by the thump and the force F exerted by the four fingers . Both forces act perpendicular to the tray , which is being held parallel to the ground
Physics Rotational Mechanics Level: High School
Rotational equilibrium
A uniform plank of length 4.6 m and weight 225 N rests horizontally on two supports , with 1.1 m of the plank hanging over the right support ( see the figure at “click here”) . To what distance x can a person who weighs 460 N walk on the overhanging part of the plank before it just begins to tip ?
Physics Rotational Mechanics Level: High School
The drawing at “click here” shows a jet engine suspended beneath the wing of an airplane . The weight W of the engine is 9300 N and acts as shown in the drawing. In flight the engine produces a thrust T of 69200 N that is parallel to the ground . The rotational axis in the drawing is perpendicular to the plane of the paper . With respect to this axis , find the magnitude of the torque due to each of the following forces
Physics Rotational Mechanics Level: High School
Conservation of angular momentum
A person of mass 59.3 kg stands at the center of a rotating merry-go-round platform of radius 2.33 m and moment of inertia 666 kg.m^2 . The platform rotates without friction with an angular velocity of 2.16 rad/s . The person walks radially to the edge of the platform . Calculate the angular velocity when the person reaches the edge .(a) Calculate the rotational kinetic energies of the system of platform plus person before and after the person’s walk .
Physics Rotational Mechanics Level: High School
What is the angular moment of a figure skater spinning (with arms in close to her body) at 3.34 revolutions per second , assuming her to be a uniform cylinder with a height of 1.30 m , a radius of 15.9 cm , and a mass of 50.0 kg .(a) How much torque is required to slow her to a stop in 4.57s , assuming she does not move her arms ?
