11/10/2017 10:00 PM 94/100 11/1/201709:27 PM Print Calculator-Puno ic Table Grad

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11/10/2017 10:00 PM 94/100 11/1/201709:27 PM Print Calculator-Puno ic Table Gradeboo Question 1 of 14 Incorrect Incorrect Sapling Learning macmilan learig A weightlifter bench-presses a 140.0 kg barbell from his chest to a height equal the length of his arms 0.800 m. How much work does he do? Number 1097.6 J What is the potential energy of the barbell relative to the weightlifter's chest after he lifts the barbell? Number 1097.6 How many food calories does the weightifter use if he does this it 35 times? Assume the weightifter does no work in letting the barbell drop back to his chest Number Cal Check Answer Next"El 0 Previous Exit

Explanation / Answer

Here,

mass , m = 140 Kg

h = 0.80 m

work done by him = m * g * h

work done by him = 140 * 9.8 * 0.80

work done by him = 1098 J

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relative to chest

gravitational potential energy = work done by lifter

gravitational potential energy = 1098 J

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total energy used = 35 * 1098 J

total energy used = 35 * 1098/4186 Cal

total energy used = 9.2 Cal

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