4.Jessica Diggins a US world champion cross country skier is participating in the winter Olympic games. Over a 200m stretch in her race she increases her speed with a constant acceleration from 5.1 m/s to 6.2 m/s over a period of 25 seconds. What is her acceleration

Explanation:

Given that,

Initial speed, u = 5.1 m/s

Final speed, v = 6.2 m/s

Time, t = 25 s

We need to find acceleration. We know that,

acceleration = rate of change of velocity

So, her acceleration is .

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia