Explanation:
1D motion is motion in only one direction. To put it simply, it's motion along a line. For example, a train on a straight track has 1D motion.
2D motion is motion in two directions. A good example of this is a projectile launched at an angle. It has both vertical motion and horizontal motion.
All of the rivers in the United States are not monitored closely for pollution levels.
The statement in the question is False
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Explanation:</u></h3>
Not all rivers in the United States are closely monitored for their pollution levels. There are volunteers who take responsibility of checking water bodies such as lakes, rivers, streams etc. They take the next step required after finding a water body contaminated.
But to say that all the rivers receive the same amount of attention and action is incorrect. To ensure that all the rivers are clean and pollution free, it would require a lot of man power in the said department which would collect the water samples from all these rivers and send it to labs for checking the pollution level of the particular river. It can be said that the rivers which are situated beside an industrial site, close to a town, will be the priority for checking pollution levels as it would directly cause harm to a small set of population if the toxicity is at an increased level.
The ball's maximum potential energy at point-R.
(Potential energy depends on height.)
Answer:
The wavelength is 173 nm.
Explanation:
This kind of phenomenon is known as photoelectric effect, it occurs when photons of light inside the metal surface and if they have the right amount of energy electrons absorb it and got expelled from the metal as photo electrons. The maximum kinetic energy of that photo electrons is given by the expression:
(1)
With E the energy of the photon and Φ the work function of the material. The work function is a value characteristic of each material and is related with how much the electron is attached to the material, the energy of the photon is the Planck's constant (h=
) times the frequency of light (
) , then (1) is:
(2)
The frequency of an electromagnetic wave is related with the wavelength (
) by:
(3)
with c the velocity of light (c=
)
Using (3) on (2):
Solving for 
:
That's the work function of the metal we're dealing. So now if we want to know the wavelength to obtain the double of the kinetic energy we use:
Solving for :
Answer:
Explanation:
The average speed is defined as:
Using the equations for uniformly accelerated motion, we calculate the runner's acceleration:
Now, we can calculate the distance that the runner travels:
Finally, we calculate the runner's average speed:
