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Furkat [3]
4 years ago
11

The minimum energy needed to eject an electron from a sodium atom is 4.41 x 10-19 j. what is the maximum wavelength of light, in

nanometers, that will show a photoelectric effect with sodium?
Physics
1 answer:
Minchanka [31]4 years ago
5 0
The energy of an electron as it is ejected from the atom can be calculated from the product of the Planck's constant and the frequency of the light energy. We can calculate the wavelength from the frequency we can calculate. We do as follows:

E = hv
 4.41 x 10-19  = 6.62607004 × 10<span>-34 (v)
v = 6.66x10^14 /s

wavelength = speed of light / frequency
</span>
wavelength = 3x10^8 / 6.66x10^14
wavelength = 4.51x10^-7 m = 450.75 nm
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A river has a steady speed 0.500 m/s. A student swims upstream a distance of1.00 km and swims back to the starting point. a) If
Ivahew [28]

Answer:

a) 33.6 min

b) 13.9 min

c)  Intuitively, it takes longer to complete the trip when there is current because, the swimmer spends much more time swimming at the net low speed (0.7 m/s) than the time he spends swimming at higher net speed (1.7 m/s).


Explanation:


The problem deals with relative velocities.

  • Call Vr the speed of the river, which is equal to 0.500 m/s
  • Call Vs the speed of the student in still water, which is equal to 1.20 m/s
  • You know that when the student swims upstream, Vr and Vs are opposed and the net speed will be Vs - Vr
  • And when the student swims downstream, Vr adds to Vs and the net speed will be Vs + Vr.

Now, you can state the equations for each section:

  • distance = speed × time
  • upstream: distance = (Vs - Vr) × t₁ = 1,000 m
  • downstream: distance = (Vs + Vr) × t₂ = 1,000 m

Part a). To state the time, you substitute the known values of Vr and Vs and clear for the time in each equation:

  • (Vs - Vr) × t₁ = 1,000 m
  • (1.20 m/s - 0.500 m/s) t₁ = 1,000 m⇒ t₁ = 1,000 m / 0.70 m/s ≈ 1429 s
  • (1.20 m/s + 0.500 m/s) t₂ = 1,000 m ⇒ t₂ = 1,000 m / 1.7 m/s ≈ 588 s
  • total time = t₁ + t₂ = 1429s + 588s =  2,017s
  • Convert to minutes: 2,0147 s ₓ 1 min / 60s ≈ 33.6 min

Part b) In this part you assume that the complete trip is made at the velocity Vs = 1.20 m/s


  • time = distance / speed = 1,000 m / 1.20 m/s ≈ 833 s ≈ 13.9 min

Part c) Intuitively, it takes longer to complete the trip when there is current because the swimmer spends more time swimming at the net speed of 0.7 m/s than the time than he spends swimming at the net speed of 1.7 m/s.

6 0
4 years ago
What is the primary role of the respiratory system in living organisms?
Papessa [141]
I think its b but not sure
3 0
3 years ago
.... is increasing the temperatures of earths oceans and atmosphere, leading to more intense storms of all types, including hurr
kirza4 [7]
I think with the increasing of temperatures of earths oceans and atmosphere is causing climate change and global warming. When the ocean heats up a lot of sea animals die and with the hot temps in the atmosphere is causing rare hot tempatures in some places in the world.
It can cause some intense storms but it mostly heats up the world and cause a lot of problems.

I hope i answered your question right.
5 0
4 years ago
A bus makes a 10-kilometer journey through town. It's top speed is 50 km/h and it's mean speed is 16kn/h. Explain why these spee
Maru [420]

Answer:

speed are different at different places

Explanation:

because it's top speed is 50km/h,so it's initial speed may be less. when it covers some distance it's speed changes again. then we have given a mean speed .mean speed means sum of all speed divided by sum of total time.so the mean speed and final speed differs from each other

6 0
4 years ago
Select the statements that correctly interpret the data in this heating curve.
tekilochka [14]

The consistent temperature indicated by section 2 represents the flow of energy lost as the water freezes.

Section 2 indicates that energy is being utilized to bring all molecules to the melting point.

Section 4 indicates that the temperature is stable until all molecules reach the boiling point.

The increasing temperature in section 5 indicates that molecular motion is increasing.

Explanation:

The figure is missing: find it in attachment.

The graph represents the temperature of a block of ice as heat is continuously supplied to it.

At the beginning (section 1), the temperature increases: in this phase, the heat supplied to the ice is used to increase the kinetic energy of vibration of the molecules of ice.

When the ice reach point A (melting point), the ice starts to melt. In this phase (section 2), the temperature of the substance remains constant, because all the heat supplied is used to break the bonds between the molecules, converting the ice into liquid water.

At point B, the ice has completely melted, and therefore we now have liquid water.

In sector 3 (between B and C), the temperature of the water increases again as we supply more and more heat: this heat, in fact, is used to increase the kinetic energy of the molecules, which move faster and faster.

Then, the water reaches the boiling point (point C): after that, the water starts to boil, (sector 4) and the heat supplied is entirely used to remove the intermolecular forces between the molecules of water; as a result, the temperature remains constant during the process.

At poind D, the water has completely boiled, and converted into gas state (steam).

After that, the temperature of the steam starts to increase again (sector 5) as more and more heat is supplied, because it is used to increase the kinetic energy of the molecules.

Therefore, the correct statements are:

The consistent temperature indicated by section 2 represents the flow of energy lost as the water freezes.

Section 2 indicates that energy is being utilized to bring all molecules to the melting point.

Section 4 indicates that the temperature is stable until all molecules reach the boiling point.

The increasing temperature in section 5 indicates that molecular motion is increasing.

3 0
3 years ago
Read 2 more answers
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