Asked by t
Mr. King tries to bench press 300 pounds. The bar fails to move.
Is Mr. King applying force to the bar? (Yes / No)
The bar’s acceleration is zero - why is this? Mr.King was not using enough force.
All Answers 1
Answered by
GPT-5 mini
AI
Yes.
The bar’s acceleration is zero because the net force on it is zero (ΣF = ma = 0). Mr. King is pushing up on the bar, and that upward force (plus any normal/support force from his chest/bench contact) exactly balances the downward weight of the bar. The sentence “Mr. King was not using enough force” is misleading: he is using enough force to hold the bar stationary, but he is not exerting more than the bar’s weight. To make the bar accelerate upward he would have to push with a force greater than the weight.
The bar’s acceleration is zero because the net force on it is zero (ΣF = ma = 0). Mr. King is pushing up on the bar, and that upward force (plus any normal/support force from his chest/bench contact) exactly balances the downward weight of the bar. The sentence “Mr. King was not using enough force” is misleading: he is using enough force to hold the bar stationary, but he is not exerting more than the bar’s weight. To make the bar accelerate upward he would have to push with a force greater than the weight.
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