# Under what conditions a person can lift a car alone? [closed]

I'm thinking about starting my work of physics with this question but do not know how to answer.

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## closed as off-topic by Dimensio1n0, John Rennie, tpg2114, Michael Brown, Chris WhiteNov 3 '13 at 3:57

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By using pulleys, levers or hydraulics...

A person must do a certain work in order to lift a car and increase its potential energy. Now, since a maximal force that a person can exert is limited, the idea is to increase a displacement / spatial dimension, i.e.

$$W = \vec{F} \cdot \vec{s}.$$

System of pulleys or lever or hydraulics do exactly that. You need smaller force, but you exert it on larger displacement / spatial dimension.

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Theoretical physicist would say that it can be done by putting this person and the car in place where gravity is not as strong as on the Earth

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The problem of positioning the force exerted is great. i.e. how does one get directly under the vehicle in a standing/lifting position, and does this 'count' as lifting a car? You could certainly attempt this at an auto-garage with the vehicle raised up on a hoist, and try to lift the already-over-head car for seconds, a few centimeters off the hoist. Still, this would require a very strong (possibly out-of-state) man and a very small car. Otherwise, levers & pulleys it is... since we have already used hydraulics for positioning, like Pygmalion said above.

How 'alone' do you mean? There is something called 'Hysterical Strength', from http://en.wikipedia.org/wiki/Hysterical_strength

It is a speculative term that is not recognized in medical academia; the concept has only a small body of anecdotal evidence to support it.

Here is an account of one such incident: http://www.dailymail.co.uk/news/article-2007972/300lbs-American-footballer-Danous-Estenor-lifts-car-save-life-trapped-truck-driver.html?ITO=1490&amp&amp

In the article above, imagine that instead the vehicle was a much smaller car like a Geo Metro or a little lighter original Mini Cooper (~635kg) (and not a huge cadillac sedan), perhaps the car may have then been feasibly FULLY lifted off the ground if the 300lb football player was that 'hysterical', although not necessary to save the man underneath in that situation.

It would follow that the strongest men in the world are the only one's who could be candidates for such a lift, and even then it's likely they would have to be 'hysterical' (i.e. at full adrenal load + other chemical reactions in the body that heretofore are undocumented due to the rarity of their occurrences) to pick up the small car 'over head', which is considered a great deal more difficult than 'thigh high' lifts. http://www.dnaindia.com/scitech/report_what-is-the-maximum-weight-a-human-can-lift_1375422

Also the drug Phencyclidine, aka PCP, allows people to perform feats of strength that severely injures them, but cannot feel the resultant pain while on the drug. However I don't think PCP has any place in physics work, as the consequences are too horrendous. I mention it only in the realm of possibility.

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