Correct answer only !

the hum (sound wave) you may have heard from a transformer has a frequency of about 100 hz and a wavelength of 3.4 m. how fast does the hum travel?

remember that v= λ ∙ f

Did you see that formula at the bottom of the question ? The one that says. V = L x f ?

That's where you can stick the numbers that the question also gives you.

L = 3.4 m

f = 100 Hz

Puttum in the formula and then it says

V = (3.4 m) (100 Hz)

The question wants to know what ' v ' is.

Do that one multiplication and you'll have it.

It's 340 m/s.

Surprise surprise ! It's the speed of sound in air.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

the area between the graph and the t axis