Answer:
The depth of focus achievable with those lenses is small.
Explanation:
A larger aperture makes it much harder to focus on more than one object. When using a telephoto lens (the ones the question is referring to), the depth of focus is very small. For example, using a telephoto lens to take a photo of a runner might get the runner in focus, but certainly not the track, or the audience behind them. If you look at photos, especially older photos, of Olympians in almost any sport you can see this.
Hope this helps!
Explanation:
Whenever an object is at its highest point, the velocity and acceleration of the object is zero.
Answer:
Length of the pendulum will be 3.987 m
Explanation:
We have given time period of the pendulum T = 8 sec
Acceleration due to gravity 
We have to find the length of the simple pendulum
We know that time period of the simple pendulum is given by



So length of the pendulum will be 3.987 m
Answer:
- The work made by the gas is 7475.69 joules
- The heat absorbed is 7475.69 joules
Explanation:
<h3>
Work</h3>
We know that the differential work made by the gas its defined as:

We can solve this by integration:

but, first, we need to find the dependence of Pressure with Volume. For this, we can use the ideal gas law


This give us

As n, R and T are constants

![\Delta W= \ n \ R \ T \left [ ln (V) \right ]^{v_2}_{v_1}](https://tex.z-dn.net/?f=%20%5CDelta%20W%3D%20%5C%20n%20%5C%20R%20%5C%20T%20%20%5Cleft%20%5B%20ln%20%28V%29%20%5Cright%20%5D%5E%7Bv_2%7D_%7Bv_1%7D%20)



But the volume is:



Now, lets use the value from the problem.
The temperature its:

The ideal gas constant:

So:


<h3>Heat</h3>
We know that, for an ideal gas, the energy is:

where
its the internal energy of the gas. As the temperature its constant, we know that the gas must have the energy is constant.
By the first law of thermodynamics, we know

where
is the Work made by the gas (please, be careful with this sign convention, its not always the same.)
So:


Answer: B
It can exist in many alloys, usually with a carbon base
Explanation:
Iron forms many alloys with a carbon base. Steel is an alloy of iron and carbon. There are many different types of steel needed for different applications. Various metals are added to tune the steel to the required properties. For instance, stainless steel contains 10-30% chromium in addition to iron and a low percentage of carbon. Steel remains an extremely versatile alloy used for many different purposes.