Explanation:
it is given that, the linear charge density of a charge, 
Firstly, we can define the electric field for a small element and then integrate for the whole. The very small electric field is given by :
..........(1)
The linear charge density is given by :


Integrating equation (1) from x = x₀ to x = infinity



Hence, this is the required solution.
The board is 2.50m high.
Why?
We can calculate how high was the board applying the Law of Conservation of Mechanical Energy. This Law states that the mechanical energy (kinematic and potential) will be conserved during the motion.
It can be described with the following formula:


At the top of the boar, the kinetic energy is equal to 0.
At the water, the potential energy is equal to 0.
So,

Hence, we have that the board is 2.50m high.
Have a nice day!
Answer:
The coefficient of kinetic friction is 0.51.
Explanation:
Given that,
Applied force, F = 75 N
Mass of a box, m = 15 kg
The acceleration of the box is 3 m/s²
We need to find the coefficient of kinetic friction. It is given by the formula as follows :

Where,
, is the normal force

So, the coefficient of kinetic friction is 0.51.
(a) 8927 mi/h
In order to calculate the average speed, we need to convert the time (t=5.0 y) into hours first. In 1 year, we have 365 days, each day consisting of 24 hours, so the time taken is:

The distance covered by the spacecraft is

Therefore, the average speed is just the ratio between the distance covered and the time taken:

(b) 35 minutes (2097 seconds)
The transmitted signals (which is a radio wave, which is an electromagnetic wave) travels back to the Earth at the speed of light:

Since 1 miles = 1609 metres, the distance covered by the signal is

So, the time taken by the signal will be

And since 1 minute = 60 sec, the time taken is

Answer: The temperature increases on the stratosphere with the altitude, given that absorption of the ultraviolet rays by the ozone.
Explanation: On the stratosphere, the water vapor and the umidity are almost nonexistents and, in view of the absorption of ultraviolet rays by the ozon, the temperature increases, reaching 35,6º Fahrenheit.
The ozone is a unusual type of oxygen molecule. In the stratosphere, the ozone appears on a large scale and warms it up by the absorption of the ultraviolet rays energy.