A 58 kg skip attached to a steel rope on a crane is used to hoist bricks from the ground to the top of a construction site. The steel rope is wound onto a lifting drum with a diameter of 700 mm and rotational frequency of 69 revolutions per minute. The lifting drum is situated on the top floor. Calculate the efficiency of the lifting generator, if the electric motor power of 9000 W is needed to drive the loaded skip.

A 58 kg skip attached to a steel rope on a crane is used to hoist bricks from the ground to the top of a construction site. The steel rope is wound onto a lifting drum with a diameter of 700 mm and rotational frequency of 69 revolutions per minute. The lifting drum is situated on the top floor. Calculate the efficiency of the lifting generator, if the electric motor power of 9000 W is needed to drive the loaded skip.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Use an energy method to obtain the expression for the natural frequency of thesystem shown.
. A pulley used to transmit power by means of ropes has a diameter of 3.5 m and has grooves of 45° angle. The angle of contact is 160° and coefficient of friction between the ropes and groove sides is 0.3. The maximum possible tension in the rope is 1000 N ad the mass of rope is 1.5 kg per metre length. What is the speed of the pulley in rpm and the power transmitted if the condition of maximum power prevail? 10
A loaded governor of the Porter type has equal arms and links each 250 mm long. The mass of each ball is 2 kg and the central mass is 12 kg. When the ball radius is 150 mm, the valve is fully open and when the radius is 185 mm, the valve is closed. Find the maximum speed and the range of speed. If the maximum speed is to be increased 20% by an addition of mass to the central load, find what additional mass is required.
mo A 100 kg machine has an unbalanced mass of 1 kg, which is rotating at a constant speed of 500 rpm at an offset of 0.2 meters. Calculate the amplitude of the centrifugal force that will be acting on the ground if the machine is directly anchored to the ground. Also calculate the stiffness of the elastic pad that will be placed under the machine such that only 1/10 of this force will be transmitted to the ground. 0-ot m
A flywheel absorbs 2500 ft-lb of energy at a coefficient of fluctuation of 0.10. The mean diameter of the flywheel is 72 inches. The weight of the arms and hub is 12 % of the rim weight. The mean rim speed is 80 fps. Consider the specific weight of the flywheel as γ = 0.26 lb/in3. A. Find the mean rpm of the rim. B. Determine the weight of the rim. C. What is the cross sectional area of the rim?
A spring is stretched (250mm) to the equilibrium position when attached to mass of 15 kg. If the object is initially displaced 100mm downward from its equilibrium position and given a velocity of 150 mm/sec downward. Find the displacement at any time? Use g-9.81 m/sec?.
4. A loaded governor of the Porter type has equal arms and links each 250 mm long. The mass of each ball is 2 kg and the central mass is 12 kg. When the ball radius is 150 mm, the valve is fully open and when the radius is 185 mm, the valve is closed. Find the maximum speed and the range of speed. If the maximum speed is to be increased 20% by an addition of mass to the central load, find what additional mass is required. [Ans. 193 r.p.m.; 16 r.p.m.; 6.14 kg]
An electric motor with a mass of 20 kg is placed in the middle of a beam that is jointly connected on both sides. Rotor its unbalance is equivalent to a mass of 0.3 kg at a distance of 0.020 m from the axis of rotation. Due to the electric motor force acting on the beam t Sin F F  0 . The rotor is rotating at an angular speed of  = 40 rad / sec. Engine under the influence of force Find the displacement amplitude at the point where it is located (in the middle). The beam mass will be neglected. The beam has a modulus of elasticity E = 200000000000 N / m2 (200 GPa).
A machine with a total mass of 2000 kg has a rotor with an out of balance force equivalent to 0.2 kg at 0.5 m radius rotating at 3000 rev/min. Calculate the stiffness and mass of an undamped vibration absorber which could be connected to the machine to eliminate transmission of force to the foundation at the operating speed, if the maximum deflection of the absorber spring is to be limited to 8 mm. [Ans 1234 kN/m, 12.5kg]
One end of a light uniform rod is attached to a wall by africtionless hinge. The rod is held in a horizontal position by a wire thatruns from the other end of the rod to the wall. The wire has length 2.00 mand makes an angle of 30.0° with the rod. A block with mass m is suspendedby a light rope attached to the middle of the rod. The transversefundamental standing wave on the wire has frequency f. The mass m isvaried and for each value the frequency is measured. You plot f 2 versus mand find that your data lie close to a straight line with slope 20.4 kg -1 # s-2.What is the mass of the wire? Assume that the change in the length of thewire when the tension changes is small enough to neglect.
In order to choose a motor to deflect a flap into a flow around a missile consider the followingdiagram. Compute the torque to be applied by the servo motor fixed to the pin at point A whichwill keep the tip of the flap up 5 mm if the flow has magnitude Fo = 100 kN/m. The flap is 30mm long. Express you answer as a number in N-m.
A 500 pound weight is attached to a cable that is being lifted by a 10 inch diameter drum. The 48V DC motor selected has a no-load angular velocity of 800 RPM and a stall torque of 500 inch-pounds. A gearbox has been designed to spin the drum as quickly as possible. Assume that there are no friction losses in this system. Determine the maximum mechanical power that the motor can produce in watts. The gearbox output torqueis 100 in lbs.