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2 years ago

One student did an experiment with sand, rocks, pebbles, and water. The steps of the experiment are shown below.

1 answer:

3 0

The intended observation in this experiment is to check the flow of water through the cotton cloth when pouring the water through different material (sand, rocks and pebbles).
We will observe that the rate of water flow changes depending on which material it is flowing through.
The used materials in this experiment (sand, rocks and pebbles) are the same as those forming different layers of the earth.

Therefore, based on the above explanation, we can infer that the best answer is:
D. groundwater moves at different rates through different layers of the Earth

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A fisherman is watching water waves ripple past his boat. How could he determine the wavelength of the water waves?

natta225 [31]

Wavelength can be calculated using the following formula: wavelength = wave velocity/frequency. Wavelength usually is expressed in units of meters.

7 0

2 years ago

You place your hands over a steaming bowl of soup to warm them. Which type of heat transfer are you experiencing?

Pani-rosa [81]

There could be a little bit of conduction through the air that's between the soup and your hand. But it's very small, because air is not a good conductor of heat.

It's mostly convection ... hot air and steam rising from the soup to your hand.

Then, of course, there HAS to be some conduction when the hot gases reach your hand ... their heat has to soak into your skin, and that's conduction.

8 0

2 years ago

Read 2 more answers

Two speakers, A and B, produce identical sound waves. A listener is 3.2 m away from speaker A. The listener finds the lowest fre

earnstyle [38]

Answer:

0.83 m or 5.57 m

Explanation:

Destructive interference will occur when the distances from the speakers differ by 1/2 wavelength.

The length of 1 cycle of 72.4 Hz is ...

λ = v/f = (343 m/s)/(72.4 Hz) ≈ 4.738 m

So, the distance of the listener from speaker B is ...

3.2 m ± (4.738 m)/2 = {0.83 m, 5.57 m} . . . either of these distances

_____

The location could be at additional multiples of 4.738 m, but we think not. The sound intensity drops off with the square of the distance from the speaker, so identical sound waves from the speakers will sound quite different at different distances from the speakers. For best interference, the distances need to be as close to the same as possible. That will be at 3.2 m and 5.57 m.

_____

Comment on the speed of sound

We don't know what speed you are to use for the speed of sound. We have used 343 m/s. Some sources use 340 m/s, which will give a result different by 2 or 3 cm.

8 0

2 years ago

An electron is trapped in a square well of unknown width, L. It starts in unknown energy level, n. When it falls to level n-1 it

Lady bird [3.3K]

Answer:

(1) En to n-1 = 0.55 ev

(2) En-1 to n-2 = 0.389 ev

(3) ninitial =4

(4) L =483.676 ×10^-11 nm

(5) λlongest= 1773.33 nm

Explanation:

Detailed explanation of answer is given in the attached files.

4 0

2 years ago

The resistivity of a metal increases slightly with increased temperature. This can be expressed as rho=rho0[1+α(T−T0)], where T0

Readme [11.4K]

Answer:

I = ΔVA[1 - α (T₀ - T)]/Lρ₀

Explanation:

We have the following data:

ΔV = Battery Terminal Voltage

I = Current through wire

L = Length of wire

A = Cross-sectional area of wire

T = Temperature of wire, when connected across battery

T₀ = Reference temperature

ρ = Resistivity of wire at temperature T

ρ₀ = Resistivity of wire at reference temperature

α = Temperature Coefficient of Resistance

From OHM'S LAW we know that;

ΔV = IR

I = ΔV/R

but, R = ρL/A (For Wire)

Therefore,

I = ΔV/(ρL/A)

I = ΔVA/ρL

but, ρ = ρ₀[1 + α (T₀ - T)]

Therefore,

I = ΔVA/Lρ₀[1 + α (T₀ - T)]

I = [ΔVA/Lρ₀] [1 + α (T₀ - T)]⁻¹

using Binomial Theorem:

(1 +x)⁻¹ = 1 - x + x² - x³ + ...

In case of [1 + α (T₀ - T)]⁻¹, x = α (T₀ - T).

Since, α generally has very low value. Thus, its higher powers can easily be neglected.

Therefore, using this Binomial Approximation, we can write:

[1 + α (T₀ - T)]⁻¹ = [1 - α (T₀ - T)]

Thus, the equation becomes:

I = ΔVA[1 - α (T₀ - T)]/Lρ₀

3 0

2 years ago