PHYS 1050 Exam 2

You are a deep sea diver and are carrying out pressure tests on your air tanks, which are required by inspection rules. A gas cylinder is filled with a gas at a temperature of 300 K and pressure 200000 Pa. The temperature of the gas is then raised to 400 K. What is the new pressure?

266667 Pa

An ideally efficient heater adds 1100 J of heat to a warm room. How much work does it perform if it removes 1400 J of energy from the outdoors?

300 J

If you put a warm bottle of wine in a container of ice water, the wine will cool but the ice water won't become warmer. Where is the wine's thermal energy going?

It melts some of the ice

How would a frisbee fly on the airless moon?

It would fly just like a rock thrown at the same velocity

The surface of the moon is exposed to full solar radiation because it has no atmosphere. Why then does the moon not heat up endlessly until it disintegrates?

Its temperature rises until it is able to radiate heat away into space as fast as it arrives from the sun

Suppose you have gotten a new job where you have to design balls that fly through the air with as little resistance as possible. You know that in front of the ball there is laminar flow, so in the back of the ball there should be

Laminar flow, so the leading and trailing pressure environments are similar

When a fish is floating motionless near the bottom of a lake, what forces act on it, and what is the net force?

Lift and weight, for a net force zero

Why does fuzz on a tennis ball help it travel farther when hit?

The fuzz causes turbulence on the leading edge of the ball only, creating a topspin and propelling the ball forward due to Magnus Effect

A doctor can study a patients circulation by imaging the infrared light emitted by the patient's skin. Tissue with poor blood flow is relatively cool. What changes in the infrared emissions would indicate such a cool spot?

The infrared emissions from the cool spot would be less bright and shifted toward longer wavelengths

Soil heats up much faster than water when the two are exposed to sunlight. Use that fact and your understanding of heat transfer to predict which way the wind will blow near the surface of the earth as the sun rises near the seashore.

The surface wind will blow from the land toward the water

For an object that sinks in a fluid,

The weight of fluid displaced is less than its weight.

True or False? The pressure on a fluid in a pipe will be lower in regions where the fluid moves faster.

This is only true in pipes oriented horizontally

Suppose you had a very long straw that could reach from a cup of water on the ground level to the top of a very tall building. When you suck on the straw in order to bring water up,

You could bring water up to only a certain height in the straw because the atmosphere pushes down on the surface of the water by a given amount

In a car engine, the compression stroke involves the piston compressing the air/gas mixture so rapidly that virtually no heat loss can occur. In the compression stroke, the air/gas mixture

heats because work is being done on the air/gas mixture

The neighborhood children are playing and one has lost a pocketful of change. As a result they all decide to do a close inspection of the sidewalk. They notice that there are gaps in between the sidewalk filled with a felt like material. The gaps will prevent

high stress due to thermal expansion

The "strokes", or "cycles" in a four stroke engine are

induction, compression, power, exhaust

You stop for a cappuccino at a coffee shop and notice that the tiny white bubbles of steamed milk remain on the surface of the coffee. These air-filled bubbles stay where they are, rather than descending into the coffee or rising into the air, because they are

less dense than the coffee but more dense than the air above the coffee

A popular classroom demo is to place a gas can on a burner and boil water in it. Left unchecked this has the potential to be a very boring demo. However, the can is removed from the flame and turned upside down in a dish containing room-temp water. After it cools down, the can will

shrivel up, since the atmosphere exerts more force on the can as it cools

A thermoelectric cooler is a type of heat pump that uses electric power to move heat against its natural direction of flow. In other words, it takes energy from a system and transfers it to another system which is at a higher temperature. In such a heat pump

the cooler requires power input because the flow heat from a cool region to a warm region alone would decrease the entropy(disorder) of the system

Fill in the Blank: Suppose you have an aquarium and into the water you have dropped a solid plastic decoration and a rock- about the same volume as the plastic one but twice as dense. Both are totally submerged and falling toward's the aquariums bottom. The buoyant force on the plastic object is about ____ that on the rock. Assume the density of plastic is 60 kg/m^3 and that the density of the rock is 2,500 kg/m^3

the same as