A uniform 5.50-kg square solid wooden gate 2.00 m on each side hangs vertically from a frictionless pivot at its upper edge. A 1.00-kg raven flying horizontally at 5.00 m/s flies into this door at its center and bounces back at 2.00 m/s in the opposite direction. What is the angular speed of the gate just after it is struck by the unfortunate raven?

ω = 0.9545 rad/s

Explanation:

In this question, angular momentum is conserved.

Thus;

Initial angular momentum = final angular momentum.

Thus, L_1 = L_2

So,

m•v1•l = -m•v2•l + I_gate•ω

So;

m•v1•l + m•v2•l = I_gate•ω

l = l/2

So,we now have;

(ml/2)•(v1 + v2) = I_gate•ω

Now, I_gate is expressed as Ml²/3

Where M is mass of gate = 5.5 kg.

So,

(ml/2)•(v1 + v2) = (Ml²/3)•ω

ω = [3ml(v1 + v2)]/2Ml²

This will reduce further to;

ω = [3m(v1 + v2)]/2Ml

Where m is mass of raven = 1 kg

v1 = 5 m/s

v2 = 2 m/s

l = 2m

So;

ω = [3(1)(5 + 2)]/(2×5.5×2)

ω = 3×7/22

ω = 0.9545 rad/s

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

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