Solving Your Crate Loading Problem - Get the Right Answer!

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To determine the number of 30-kg crates that can be loaded onto a truck in one minute for an average power output of 0.50 hp, the calculation involves converting horsepower to watts and calculating the work done to lift the crates. The average power output is 373 W, leading to a total work of 22,380 J over one minute. The work required to lift one crate is calculated as 264.6 J. Dividing the total work by the work per crate results in approximately 84.58 crates, which rounds to 85. The discussion centers on confirming the accuracy of this calculation and addressing concerns about the correctness of the answer.
iwonde
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Your job is to lift 30-kg crates a vertical distance of 0.90 m from the ground onto the bed of a truck. How many crates would you have to load onto the truck in one minute for the average power output you use to lift the crates to equal 0.50 hp?

The equation that I used is: P_av = (delta W)/ (delta t)
Since 1hp = 746W --> 0.50hp = 373 W
delta W = (P_av)(delta t) = 373 W x 60 s = 22380 J
Work required to lift one crate = mgh = 30kg x 9.8 m/s^2 x 0.9m = 264.6J
Number of crates = 22380J / 264.6 J = 85

85 is not the correct answer. What did I do wrong?
Thanks.
 
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I get 84.58, which rounds to 85, same as you.

What makes you think this answer is wrong?
 

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