A student sits on a freely rotating stool holding two dumbbells, each of mass 2.97 kg (see figure below). When his arms are extended horizontally (Figure a), the dumbbells are 1.09 m from the axis of rotation and the student rotates with an angular speed of 0.749 rad/s. The moment of inertia of the student plus stool is 2.57 kg. m² and is assumed to be constant. The student pulls the dumbbells inward horizontally to a position 0.305 m from the rotation axis (Figure b). Wi a b @f (a) Find the new angular speed of the student. rad/s (b) Find the kinetic energy of the rotating system before and after he pulls the dumbbells inward. Kbefore = J Kafter = J

A student sits on a freely rotating stool holding two dumbbells, each of mass 2.97 kg (see figure below). When his arms are extended horizontally (Figure a), the dumbbells are 1.09 m from the axis of rotation and the student rotates with an angular speed of 0.749 rad/s. The moment of inertia of the student plus stool is 2.57 kg. m² and is assumed to be constant. The student pulls the dumbbells inward horizontally to a position 0.305 m from the rotation axis (Figure b). Wi a b @f (a) Find the new angular speed of the student. rad/s (b) Find the kinetic energy of the rotating system before and after he pulls the dumbbells inward. Kbefore = J Kafter = J

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter1: Introduction To Statics

Section: Chapter Questions

Problem 1.20P: Find the elevation h (km) where the weight of an object is one-tenth its weight on the surface of...

See similar textbooks

Similar questions

Find the elevation h (km) where the weight of an object is one-tenth its weight on the surface of the earth.
Two uniform, solid spheres (one has a mass M1= 0.3 kg and a radius R1= 1.4 m and the other has a mass M2 = 2M, kg and a radius R2= 2R;) are connected by a thin, massless rod of length L= 4R1. Find the moment of inertia (in kg.m2) about the axis through the center of sphere 1. (Igphere = MR?). Axis of rotation R, R2 a. 59.74 b. None of the choices O c. 117.13 d. 97.37 O e. 45.04
A wheel with rotational inertia 48 kg.m2 is mounted on a fixed, frictionless axle. The angular speed of the wheel is increased from zero to 59 rad/s in 12-s. What is the average net torque/Moment in N.m on the wheel during this time interval?
A uniform rod (mass = 1.8 kg) is 1.5 m long. The rod is pivoted about a horizontal, frictionless pin through one end. The rod is released from rest in a horizontal position. What is the angular speed of the rod (in rad/s) when the rod makes an angle of 23° with the horizontal?. The moment of inertia of the rod about this axis is given by (1/3)ML2.
A riveting machine is used for riveting sheets of 20 mm thickness. The machine is driven by a geared motor of 5 kW. The mass moment of inertia of the rotating parts of the machine attached to flywheel is found to be 10 kg- m². At the beginning of the operation, the flywheel is making 15 r.p.s. If making one rivet takes 30 KN-m of energy in 5 second, then find the reduction of speed of the flywheel
A student sits on a rotating stool holding two 3.0 kg objects. When his arms are extended horizontally, the objects are 1.0 m from the axis of rotation, and he rotates with an angular speed of 0.75 rad/s. The moment of inertia of the student plus stool is 3.0 kg•m and is assumed to be constant. The student then pulls the objects horizontally to 0.50 m from the rotation axis. (a) Find the new angular speed of the student. 1.907 Your response differs from the correct answer by more than 10%. Double check your calculations. rad/s (b) Find the kinetic energy of the student system before and after the objects are pulled in. before after
A 5kg lacrosse stick has a moment of inertia about a transverse axis through its center of gravity of 8 kg.m2. When a player swings the stick at an opponent, the axis of rotation is through the end of stick, 80 cm from the center of gravity of the stick. What is the moment of inertia relative to this swing axis? A 4 kg lacrosse stick has a radius of gyration of 60cm about a transverse axis through its center of gravity. When a player swings the stick at an opponent, the axis of rotation is through the end of stick, 120cm from the center of gravity of the stick. What is the moment of inertia relative to this swing axis?
A shaft caries four rotating masses A, B, C and D which are completely balanced. The masses B, C and Dare 50kg, 80kg and 70kg respectively. The masses C and D make angles of 90° and 195° respectively with mass B in the same sense. The masses A, B, C and D are concentrated at radius 75mm,100mm,50mm and 90mmrespectively.The plane of rotation of masses B and C are 250mm apart. Determine the magnitude of mass A and its angular position the position of planes A and D.
A car is moving on a curved horizontal road of radius 100 m with a speed of 20 m/s. The rotating masses of the engine have an angular speed of 100 rad/s in clockwise direction when viewed from the front of the car. The combined moment of inertia of the rotating masses is 10 kg-m². The magnitude of the gyroscopic moment (in N-m) is
A shaft has three eccentric of mass 1 kg each. The central plane of the eccentrics is 50 mm apart. The distances of the centers from the axis of rotation are 20, 30 and 20 mm and their angular positions are 120 apart. If the shaft is balanced by adding two masses at a radius of 70 mm and at a distance 100 mm from the central plane of the middle eccentric, find the amount of the masses and their angular positions.
Question 5 A four-wheeled automobile car has a total mass of 1000 kg. The moment of inertia of each wheel about a transverse axis through its center of gravity is 0.5 kgm?. The rolling radius of the wheel is 0.35 m. The rotating and reciprocating parts of the engine and the transmission system are equivalent to a moment of inertia of 2.5 kgm?, which rotates at five times the road-wheel speed. The car is travelling at a speed of 100 km/hr on a plane road. When the brakes are applied, the car decelerates at 0.5g [g= Gravity]. There are brakes on all four wheels. Calculate: a) The energy absorbed by each brake b) The torque capacity of each brake.
Change of Ttork required by a machine for rotational movement with rotation angle T(0)=5000[1+5cos(30)-6sin (30)] (Nm ) is given as. The rotation speed of the machine is below 711 r/min mass moment of inertia required to allow it to move without landing and without leaving above 729 rpm find its value. Please select one: 2 A.241,473 kg-m B.119,592 kg-m2 2. C.183,181 kg-m D.221,264 kg-m 2. E.165,845 kg m 2. F.262,223 kg * m G.126,304 kg m H.150,179 kg-m 2 1,201, 759 kg-m J.136,759 kg-m