Average power needed to lift an object

AI Thread Summary
To calculate the average power needed to lift a 115kg weight to a height of 1.95m in 1.25 seconds, the average velocity is determined to be 1.56 m/s. The incorrect acceleration calculation was pointed out, suggesting the use of the equation s = ut + 0.5at^2 for a more accurate result. Alternatively, the power can be calculated using the formula mgh/time, which simplifies the process. The initial attempt yielded a power output of approximately 1,982 watts. Correcting the approach to find acceleration or using the constant velocity assumption can provide clearer insights into the average power required.
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Homework Statement



A weightlifter raises a 115kg weight from the ground to a height of 1.95m in 1.25 seconds. What is the average power of this maneuver.

Homework Equations



m = 115kg
Change in Y = 1.95m
time = 1.25 seconds


The Attempt at a Solution



V = 1.95/1.25 = 1.56 m/s
a = 1.56/1.25 = 1.248 m/s/s
mg = (115)(-9.8) = -1127 N

Net Force Of Fy = (115)(1.248)
Net Fy = 143.52
Force of maneuver:
143.52 = -1127 + x
Force of maneuver = 1270.52

Work = 1270.52 * 1.95
Work = 2477.514

P = 2477.514 / 1.25 = 1,982.0112

Help?
 
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Your acceleration is wrong, the 'V' you worked out was the average velocity, you can work out the acceleration using s = ut +0.5at^2.

Alternatively assume the lift is of constant velocity and say:

mgh / time = power
 
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