GCSE physics

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GuruOfMaths
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#1
Report Thread starter 3 years ago
#1
Newtons third law states every action has an equal and opposite reaction
Ok so
If we put a fat person on a concrete roof he will stay there
If we put a fat person on a straw (or anything weak) he will fall through even the straw roof is supposed to exert the same force as the concrete roof does on the fat person.
Pls explain
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Sinnoh
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#2
Report 3 years ago
#2
Moved to Physics.

Any material or structure has a maximum amount of load it can withstand before breaking. If a meteorite landed on a concrete roof then the concrete roof would be smashed to pieces.
If the structure were able to withstand that load, then it would provide an equal and opposite support force. But it can't, so it doesn't.
If you put an ant on a pile of straw or on a concrete roof, it would be supported either way as its weight is extremely tiny and so won't break the straw.

So then you might ask "So it's not true that every force results in an equal and opposite force?"

When something falls, if you disregard air resistance, then it's only gravity that's acting. But a falling pen exerts a gravitational force on the Earth just as the Earth exerts a gravitational force on the pen causing it to fall. So when something falls, the Earth actually moves a tiny tiny amount, which results in momentum being conserved.

So, regardless, every force causes an equal and opposing force.
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GuruOfMaths
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#3
Report Thread starter 3 years ago
#3
(Original post by Sinnoh)
Moved to Physics.

Any material or structure has a maximum amount of load it can withstand before breaking. If a meteorite landed on a concrete roof then the concrete roof would be smashed to pieces.
If the structure were able to withstand that load, then it would provide an equal and opposite support force. But it can't, so it doesn't.
If you put an ant on a pile of straw or on a concrete roof, it would be supported either way as its weight is extremely tiny and so won't break the straw.

So then you might ask "So it's not true that every force results in an equal and opposite force?"

When something falls, if you disregard air resistance, then it's only gravity that's acting. But a falling pen exerts a gravitational force on the Earth just as the Earth exerts a gravitational force on the pen causing it to fall. So when something falls, the Earth actually moves a tiny tiny amount, which results in momentum being conserved.

So, regardless, every force causes an equal and opposing force.
wow thanks a lot
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