Calculating Energy Transfer and Work Done by a Crane

AI Thread Summary
The discussion revolves around calculating the potential energy gained by a car lifted by a crane, which is determined using the formula Eg = mgh, resulting in 294,000 J. The energy transferred by the crane to the car is also 294,000 J, indicating that the crane does positive work on the car. There is confusion regarding the concept of negative energy transfer and its implications, with a question raised about whether this equates to the crane taking energy from the car. Additionally, the impact of friction and other losses on the work done by the crane is questioned, highlighting the need for more data. Overall, the calculations emphasize the relationship between energy transfer and work in lifting scenarios.
Lolagoeslala
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Homework Statement


A creane lifts a 1500 kg car straight 20 m [up]
How much potential energy does the car gain?
How much energy does the crane transfer to the car?
How much work does the crane do?



The Attempt at a Solution


How much potential energy does the car gain?
Eg = mgh
Eg = (1500 kg)(9.8m/s^2)(20m)
Eg = 294000 J

How much energy does the crane transfer to the car?
Eg = - 294000 J

How much work does the crane do?
I am not sure
 
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Lolagoeslala said:
How much energy does the crane transfer to the car?
Eg = - 294000 J
If A were to transfer a negative amount of energy to B, would that not be the same as taking energy from B?
How much work does the crane do?
I am not sure
In the absence of any data concerning losses due to friction etc., what do you think the answer is?
 

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