What physics concept underlies these three observations? When passing an oncomin
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Question
What physics concept underlies these three observations? When passing an oncoming truck on the highway, your car tends to sway toward the truck. The canvas roof of a convertible automobile bulges upward when the car is traveling at high speeds. The windows of older trains sometimes break when a high-speed train passes by on the next track.
Doppler effect , Like attracts like or Bernoulli's principle Newton's third law
On a sensitive balance, weigh an empty flat thin plastic bag. Then weigh the bag when air is in it. Will the readings differ? Yes or No
Two balloons that have the same weight and volume are filled with equal amounts of helium. One is rigid and the other is free to expand as the pressure outside decreases. When released, which will rise higher?
The balloon free to expand will rise higher. The balloon that is rigid will rise higher. Both balloons will rise to the same height.
Two identical balloons of the same volume are pumped up with air to more than atmospheric pressure and suspended on the ends of a stick that is horizontally balanced.
One of the balloons is then punctured. Is the balance of the stick upset? If so, which way does it tip?
The balance will not be upset. The end supporting the punctured balloon tips upwards. The end supporting the punctured balloon tips downwards.
What change in pressure occurs in a party balloon that is squeezed to one-third its volume with no change in temperature?
Pressure increases to three times its original pressure. Pressure decreases to one half its original pressure. Pressure decreases to one third its original pressure. Pressure increases to four times its original pressure. Pressure increases to two times its original pressure.
Explanation / Answer
All are Bernouille's Principle
1...A truck, being bigger than a car causes a greater partial vacuum due to its velocity than the car.
The pressure difference between your car and the truck tends to push you towards the truck.
2...The canvas roof, at high speed, is causing a lower pressure above the car due to its curvature. The car's internal pressure causes the roof to bulge.
3....Older trains were not as sturdily built as modern ones..
Again, the passing of the high-speed train causes a partial vacuum and, the air pressure in the older train, acting against the large surface area of the window has sufficient pressure difference to blow a window out. (If the window was partly open it probably wouldn't happen).
On a sensitive balance, weigh an empty flat thin plastic bag. Then weigh the bag when air is in it. Will the readings differ?No, provided the air is not compressed. The bag with air in it weighs more, but it also has buoyant force that equals the weight of the air inside.
Rigid balloon will rise to a height at which the air density times the balloon volume equals the mass of the balloon.
Balloons cannot be 'pumped' to more than atmospheric pressure; it is in the nature of balloons to expand until the pressure of the gases inside and outside are equal. Once the elasticity limit of the balloon is exceeded, it pops of its own accord. Since the weight of the air inside the balloons is balanced by the weight of the air outside the balloons, popping one will have no effect on the balance.
If you'd used a generic 'container' instead of a balloon, then the balance would tip towards the intact container.
Pressure and volume have an inverse relationship. If P rises, V decreases in direct proportion. if the volume is forced to onethird, the pressure increases to 3 times!
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