 Lv 1222 points

# Concerned

• ### diameter and sound power?

Assuming that the diameter of the eardrum is 1 cm, what is the sound power received by the eardrum at the (a) threshold of hearing and (b) the threshold of pain.

• ### Condensation and entropy?

A process involves 0.50 kg of steam condensing to water @ 100°C. The change in entropy of the system is:

(a) Positive

(b) Zero

(c) Negative

Why?

What IS the change in entropy of the steam?

• ### isothermal expansion and entropy?

In an isothermal expansion at 27°C, an ideal gas does 30 J of work. What is the change in entropy of the gas?

• ### Thermodynamics and entropy?

In the winter, heat from a house with an inside temperature of 18°C leaks out at a rate of 20000 Joules per second. The outside temperature is 0°C. (a) What is the change in entropy per second of the house? (b) What is the total change in entropy per second of the house-outside system?

• ### Thermodynamics and gases?

A rigid container contains 1.0 mol of an ideal gas that slowly receives 2.0 × 10^4 J of hear.

Is the work done by the gas

(a) Positive

(b) Zero

(c) Negative

Why?

Is a net amount of hear added to or removed form the system and how much is involved?

• ### Pressure Depth and Volume?

A diver releases an air bubble of volume 2.0 cm³ from a depth of 15 m below the surface of the lake, where the temperature in 7.0°C. What is the volume of the bubble when it reaches just below the surface of the law, where the temperature is 20°C.

I know that the answer is 5.1 cm³, but what are the steps to reach the answer?

• ### Buoyancy..HELP?

A block of iron quickly sinks in water, but ships constructed of iron float. A solid cube of iron, 1.0m on each side is made into sheets. To make these sheets into a hollow cube that will not sink in water, what should be the minimum length of the sides of the sheets?

• ### Another Buoyancy and Weight Problem?

As steel cube 0.30 m on each side is suspended from a scale (that measure's weight in Newtons) and completely immersed in water. What will the scale read?

Note: the density of steel 7800 kg/m^3

• ### Buoyance and Weight Problem?

An object has a weight of 8.0 N in air. However, it weighs only 4.0 N in water when it is completely submerged. What is the object's density?