Answers to Even-numbered Conceptual Questions
No, because the Moon has no atmosphere to press down on the surface of the liquid.
A suction cup is held in place by atmospheric pressure.
When the cup is applied, you
push it flat against the surface you want to stick it to.
This expels most of the air in the
cup, and leads to a larger pressure on the outside of the cup.
Thus, atmospheric pressure
pushes the outside of the cup against the surface.
The balloon moves toward the front of the car.
The reason is that as the car accelerates
forward, the air inside it shifts toward the rear of the car – just as passengers are pressed
back into their seats.
This makes the pressure of the air in the car increase as one mores
from front to back.
The helium-filled balloon moves in the direction of decreasing
pressure – like any buoyant object – which in this case is toward the front of the car.
Mercury is more practical in a barometer than water because of its greater density.
such a large density, the height of the mercury column is only about 0.760 m.
of water is less than that of mercury by roughly a factor of 14.
Therefore, the height of a
water column in a barometer would be about 10 m – the height of a three-story building.
In a hot-air balloon, vertical motion is controlled by adding heat to the air in the balloon,
or by letting it cool off.
As the temperature of the air in the balloon changes, so too does
By controlling the overall density of the balloon, one can control whether it
rises, falls, or is neutrally buoyant.
Whether the block is upright or inverted, its weight is the same.
Therefore, the volume of
water that must be displaced to float the block is the same in either orientation.
result, the water level in the tank remains the same.
The total mass contained in the flask is the same before and after the string breaks.
follows that the reading on the scale will be the same.
The physics in this case is pretty “ugly”.
Ice floats in water, whether it is a house-sized
iceberg, a car-sized chunk, or a thimble-sized ice cube.
If the Earth is warming and
icebergs are breaking up into smaller pieces, each of the smaller pieces will be just as
buoyant as the original berg.
The boat is now carrying a reduced weight.
Therefore, it floats higher relative to the
The water level in the pool remains the same because the blocks of wood
displace the same amount of water whether they are in the boat or in the water.
case, they displace a volume of water with a weight equal to their weight.
The problem is that as you go deeper into the water, the pressure pushing against your
chest and lungs increases rapidly.
Even if you had a long tube on your snorkel, you would
find it difficult to expand your lungs to take a breath.
The air coming through the snorkel
would be at atmospheric pressure, but the water pushing against your chest might have
twice that pressure.
Thus, scuba gear not only holds air for you in a tank, but feeds it to
you under pressure.