The flywheel of an engine has moment of inertia 2.

5 kg•m2 about its rotation axis. What constant torque is required to bring it up to an angular speed of 400 rev/min in 8s, starting from at rest? A solid, uniform cylinder with mass 8. 25kg and diameter 15cm is spinning at 200 rpm on a thin, frictionless axle that stop the cylinder axis. You design a simple friction brake to stop the cylinder by pressing the brake against the outer rim with a normal force.

Order nowThe coefficient of kinetic friction between the brake and rim is 0. 333.What must be the applied normal force to bring the cylinder to rest after it has turned through 5. 25 rev? A 2.

2kg hoop 1. 2m in diameter is rolling to the right without slipping on a horizontal floor at a steady 3 rad/s. (a) how fast is its center moving? (b) What is the total kinetic energy of the hip? (c) Find the velocity vector of each of the following points as viewed by a person at rest on the ground: i) the highest point on the hoop; ii) the lowest point on the hoop; iii) the point on the right side of the hoop, midway between the hoop and the bottom. d) Find the velocity vector for each points in part c, except as viewed by someone moving along with same velocity as the hoop.

A solid ball is released from res and slides down a hillside that slopes downward at 65° from the horizontal. (a) What minimum value must the coefficient of static friction between the hill and ball surfaces have for no slipping to occur? (b) Would the coefficient of friction calculated in part a changed if the mass were doubled to 4kg? pic] A 392N wheel comes off a moving truck and rolls without slipping along a highway. At the bottom of a hill it is rotating at 25 rad/s. The radius of the wheel is 0.

6m, and its moment of inertia about its axis is 0. 8MR2. Friction does work on the wheel as it rolls up the hill to a stop, a height h above the bottom of the hill; this work has absolute value 3500J. Calculate h.

A playground merry-go-round has radius 2. 4m and moment of inertia 2100 kg•m2 about a vertical axle through its center, and it turns with negligible friction. a) A child applies 18N force tangentially to the edge of the merry-go-round for 15s. If the merry-go-round is initially at rest, what is its angular speed after this 15s interval? (b) How much work did the child do on the merry-go-round? (c) What s the average power supplied by the child? A 1.

5 kg grinding wheel is in the form of a solid cylinder of radius 0. 1m. (a) What constant torque will bring it from rest to an angular speed of 1200 rev/min in 2. 5s? (b) Through what angle has it turned during that time? c) Calculate the work done by the torque.

(d) What is the grinding wheel’s kinetic energy when it is rotating at 1200 rev/min? Compare your answer in part c. (a) Compute the torque developed by an industrial motor whose output is 150kW at an angular speed of 4000rev/min. (b) A drum with negligible mass, 0. 4m in diameter, is attached to the motor shaft, and the power output of the motor is used to raise a weight hanging from a rope wrapped around the drum.

How heavy a weight can the motor lift at constant speed? c) At what constant speed will the weight raise? The outstretched hands and arms of a figure skater preparing for a spin can be considered a slender rod providing about an axis through its center. His hands and arms can be combined mass 08kg. When outstretched, they span 1. 8m; when wrapped they form a cylinder of radius 25cm.

The movement of inertia about the rotation of axis of the remainder of his body is constant and equal to 0. 40kg•m2. If his original angular speed is 0. 4 rev/s, what is his final angular speed? pic] A large wooden turntable in the shape of a flat uniform disk has a radius of 2m and a total mass of 120kg.

The turntable is initially rotating at 3 rad/s about a vertical axis through its center. Suddenly, a 70 kg parachutist makes a soft landing on the turntable at a point near the outer edge. (a) Find the angular speed of the turntable after the parachutist as a particle. (b) Compute the kinetic energy of the system before and after the parachutist lands.

Why these kinetic energies are not equal?