**Your
Answer to Q442.**
Sorry, your answer is **not** correct. Did you remember to convert mass to
weight?

Help: *Fundamentals of
Sound*, Sec. 10-A.

Or would you like a **HINT**?

You should try to work out the answer on your own, but if you insist on reading it the correct answer is here

Return to Question 442.

**Hint
for Question 442:** A one kilogram mass weighs 10 Newtons on Earth.

Return to Question 442.

**Your
Answer to Q442. **Congratulations, your answer is **correct**.

If you would like, you can compare your answer to the "official" correct answer

Return to Question 442.

**Correct
Answer to Question 442:** The force exerted is 100 Newtons since each kilogram
weighs 10 Newtons on Earth. The distance through which the force is exerted
is the *vertical* height of the stairs, that is, 6 m so the work done is
100x6 = 600 Joules or answer b).

Return to Question 442.

**Your
Answer to Q444.** Sorry, your answer is **not** correct.

Help: *Fundamentals of
Sound*, Sec. 10-F.

Or would you like a **HINT**?

You should try to work out the answer on your own, but if you insist on reading it the correct answer is here

Return to Question 444.

**Hint
for Question 444:** Brightness depends on power not energy. Power is energy
per second.

Return to Question 444.

**Your
Answer to Q444 . **Congratulations, your answer is **correct**.

If you would like, you can compare your answer to the "official" correct answer

Return to Question 444.

**Correct
Answer to Question 444:** Brightness depends on power, not just energy. Power
is energy per second. So bulb A burns with a power of 100 J/5 s = 20 Watts,
B with a power of 50/2 = 25 Watts. Note that B has burned less total energy,
but has used its energy at a faster rate. The correct answer is b).

Return to Question 444.

**Your
Answer to Q445.** Sorry, your answer is **not** correct.

The correct answer is here.

Return to Question 445.

**Correct
Answer to Question 445:** c) Three. While one physicist screws in the bulb,
the other two argue over which equations to use.

Return to Question 445.

**Your
Answer to Q446.** Sorry, your answer is **not** correct. Brightness
depends on intensity.

Help: *Fundamentals of
Sound*, Sec. 10-G.

Or would you like a **HINT**?

You should try to work out the answer on your own, but if you insist on reading it the correct answer is here

Return to Question 446.

**Hint
for Question 446:** Brightness depends on intensity; intensity is power per
unit area (Watts per square meter.)

Return to Question 446.

**Your
Answer to Q446. **Congratulations, your answer is **correct**.

If you would like, you can compare your answer to the "official" correct answer

Return to Question 446.

**Correct
Answer to Question 446:** Brightness depends on intensity; intensity is power
per unit area (Watts per square meter or Watts per square centimeter). Thus
the intensity of lightbulb A is 20 W/2 cm^{2} = 10 W/cm^{2}.
Lightbulb B's intensity is 25/5= 5 W/cm^{2}. So now it is lightbulb
A which shows the brighter spot and answer a) is correct.

Return to Question 446.

**Your
Answer to Q448.** Sorry, your answer is **not** correct. How does
intensity depend on amplitude?

Help: *Fundamentals of
Sound*, Sec. 10-G.

Or would you like a **HINT**?

Return to Question 448.

**Hint
for Question 448:** Intensity depends on amplitude squared, that is, if you
double the amplitude the intensity goes up by 4 not 2.

Return to Question 448..

**Your
Answer to Q448. **Congratulations, your answer is **correct**.

If you would like, you can compare your answer to the "official" correct answer

Return to Question 448.

**Correct
Answer to Question 448:** Intensity increases like the square of amplitude,
or* I* = *I*_{0}(*A*/*A*_{0})^{2}.
Here *I*_{0} = 6 picowatts/m^{2} and *A*/*A*_{0}
= 3. Thus *I* = 6(3)^{2} = 6x9 = 54 picowatts/m^{2}. The
correct answer is b). [A picowatt is a small fraction of a Watt, namely
10^{-12} Watt.]

Return to Question 448.

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