A worker places an aluminum ladder on a horizontal concrete slab against a vertical wooden wall at 30 degrees from the vertical. The ladder has length L=5m and m=30 kg. The ladder’s CM is at a third of the length up. Worker Bob has mass M=90 kg and intends to climb up the ladder. Simultaneously, worker Charlie has mass M=90 kg and operates a rope through a single pulley to hoist a pail of mass m=30 kg. The axle of the pulley is anchored to the ladder at A=0.3 m along the ladder from the top point. Charlie is pulling the rope down with enough force to hoist the pail at uniform velocity. The mass of the pulley and rope are negligible. The friction in the pulley axle is negligible. The ladder is equipped with rubber booties and a rubber top. The kinetic friction coefficients are: rubber on dry concrete 0.9, rubber on dry wood 0.9, aluminum on wet concrete 0.2, aluminum on wet wood 0.2. Still disappointed with the ladder performance, Bob takes four old rubber boots, cuts off the tops and slides the improvised rubber galoshes over the four ends of the ladder. Assuming the same configuration as in part c but with rubber booties, what is his new safety limit (with the extra pail, under wet conditions)? The kinetic friction coefficient of rubber on wet concrete and rubber on wet wood is at least 0.45.
A worker places an aluminum ladder on a horizontal concrete slab against a vertical wooden wall at 30 degrees from the vertical. The ladder has length L=5m and m=30 kg. The ladder’s CM is at a third of the length up. Worker Bob has mass M=90 kg and intends to climb up the ladder. Simultaneously, worker Charlie has mass M=90 kg and operates a rope through a single pulley to hoist a pail of mass m=30 kg. The axle of the pulley is anchored to the ladder at A=0.3 m along the ladder from the top point. Charlie is pulling the rope down with enough force to hoist the pail at uniform velocity. The mass of the pulley and rope are negligible. The friction in the pulley axle is negligible. The ladder is equipped with rubber booties and a rubber top. The kinetic friction coefficients are: rubber on dry concrete 0.9, rubber on dry wood 0.9, aluminum on wet concrete 0.2, aluminum on wet wood 0.2. Still disappointed with the ladder performance, Bob takes four old rubber boots, cuts off the tops and slides the improvised rubber galoshes over the four ends of the ladder. Assuming the same configuration as in part c but with rubber booties, what is his new safety limit (with the extra pail, under wet conditions)? The kinetic friction coefficient of rubber on wet concrete and rubber on wet wood is at least 0.45.
Refrigeration and Air Conditioning Technology (MindTap Course List)
8th Edition
ISBN:9781305578296
Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Chapter1: Heat, Temperature, And Pressure
Section: Chapter Questions
Problem 17RQ: Convert 22C to Fahrenheit.
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A worker places an aluminum ladder on a horizontal concrete slab against a vertical wooden wall at 30 degrees from the vertical. The ladder has length L=5m and m=30 kg. The ladder’s CM is at a third of the length up. Worker Bob has mass M=90 kg and intends to climb up the ladder. Simultaneously, worker Charlie has mass M=90 kg and operates a rope through a single pulley to hoist a pail of mass m=30 kg. The axle of the pulley is anchored to the ladder at A=0.3 m along the ladder from the top point. Charlie is pulling the rope down with enough force to hoist the pail at uniform velocity. The mass of the pulley and rope are negligible. The friction in the pulley axle is negligible. The ladder is equipped with rubber booties and a rubber top. The kinetic friction coefficients are: rubber on dry concrete 0.9, rubber on dry wood 0.9, aluminum on wet concrete 0.2, aluminum on wet wood 0.2.
Still disappointed with the ladder performance, Bob takes four old rubber boots, cuts off the tops and slides the improvised rubber galoshes over the four ends of the ladder. Assuming the same configuration as in part c but with rubber booties, what is his new safety limit (with the extra pail, under wet conditions)? The kinetic friction coefficient of rubber on wet concrete and rubber on wet wood is at least 0.45.
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