A boat has a pressure difference between top and bottom of 100 N/m2.
The area is 5 m2.
What is the weight of the boat ? N
How is the upthrust = N

If a 500 N child climbs in the new pressure = N/m2.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

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