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It's a natural optical illusion just like in cases where cars would seemingly move uphill on its own because the eye interpreted it to be uphill when in reality it was slanted downward.
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Yes, the merry-go-round that was difficult for my 8 year old self to push on my own broke it's static statement and moved due to gravity.
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The car used were difficult for grown men to push yet it still happened. Do you want me to go on to psychology to express how your mind may have overridden the actual event and create a false, exaggerated, version of it?