The record number of boat lifts, including the boat and its ten crew members, was achieved by Sami Heinonen and Juha Räsänen of Sweden in 2000. They lifted a total mass of 653.2Kg approximately 4 Inches off the ground a total of 24 times. Estimate the total work done by the two men on the boat in this record lift, ignoring the negative work done by the men when they lowered the boat back to the ground.
The total work done by the two men on the boat was 15363.36J.
The total mass of the boat and the crew was
Displacement of the boat each time was
Number of time the boat was raised = 24
Work done to raise a mass m by height h is
Here g is the acceleration due to gravity of value
From equation (I), the work done to raise the boat each time was
Total work done to repeat this 24 times was
Thus the total work done was 15363.36J.
Alex and John are loading identical cabinets onto a truck. Alex lifts his cabinet straight up from the ground to the bed of the truck, whereas John slides his cabinet up a rough ramp to the truck. Which statement is correct about the work done on the cabinet– Earth system? (a) Alex and John do the same amount of work. (b) Alex does more work than John. (c) John does more work than Alex. (d) None of those statements is necessarily true because the force of friction is unknown. (e) None of those statements is necessarily true because the angle of the incline is unknown.
Let represent the direction horizontally north, represent northeast (halfway between north and east), and so on. Each direction specification can be thought of as a unit vector. Rank from the largest to the smallest the following dot products. Note that zero is larger than a negative number. If two quantities are equal, display that fact in your ranking. (a) (b) (c) (d) (e) .
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