2271

Physics Rotational Mechanics Level: High School

Circular Motion

An automobile tire has a radius of 0.280 m , and its center moves forward with a linear speed of v = 19.0 m/s .

a) Determine the angular speed of the wheel . (Assume that there is no slipping of the surfaces in contact during the rolling motion )

b) Relative to the axle what is the tangential speed of a point located 0.175 m from the axle ?




2270

Physics Rotational Mechanics Level: High School

Circular Motion

An auto race is held on a circular track . A car completes one lap in a time of 19.4 s , with an average tangential speed of 40.1 m/s . Find the following .

a) The average angular speed .

b) The radius of the track .




2269

Physics Rotational Mechanics Level: High School

Equations of Rotational Motion

The angular speed of the rotor in a centrifuge increases from 340 to 1340 rad/s in a time of 5.00 s .

a) Obtain the angle through which the rotor turns .

b) What is the magnitude of the angular acceleration ?




2268

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 ?



2267

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 .



2266

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 ?



2265

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 ?




2264

Physics Rotational Mechanics Level: High School

What is gyroscope and how is it used as a navigational aid ?



2263

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 .




2262

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 .




2261

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 ?



2260

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 .



2259

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 .




2258

Physics Misc Topic Level: Misc Level

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



2257

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

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