A small rescue helicopter has 4 blades, each 4m long and 50kg in mass, and it carries a load of 1000kg. a) Find the rotational kinetic energy in the blades when rotating at 300 rpm. b) Find the translational kinetic energy of the helicopter when it flies at 20 m/s, and compare it to the rotational energy in the blades. c) How high could the helicopter fly If all of its rotational kinetic energy could be used to lift it

A) KE_rot= 5.26 x 10^(5) J

B) KE_trans = 2 x 10^(5)J

Ratio = 0.38

C) Max height = 52.7m

Explanation:

A) We are given;

m = 50kg

r = 4m

ω = 300 revs/min = 300 x 0.1047 = 31.4 rads/s

The formula for rotational kinetic energy is given as;

KE_rot= (1/2)Iω²

Where I is moment of inertia.

Now, I = mr²/3

But since it has 4 blades, thus,

I = 4mr²/3 = 4 x 50 x 4²/3 = 1067 kg. m²

Thus, KE_rot= (1/2)(1067)(31.4)² = 5.26 x 10^(5) J

B) The formula for translational kinetic energy is given by;

KE_trans = (1/2)mv²

We are given velocity as 20 m/s

Thus,

KE_trans = (1/2)(50)(20)² = 2 x 10^(5)J

To compare this to the rotational kinetic energy, we'll take the ratio. Thus; = KE_trans/KE_rot = 2 x 10^(5)J/5.26 x 10^(5)J = 0.38

C) At maximum height,

KE_rot = PE_gravity

Thus, 5.26 x 10^(5)J = mgh

Where m is the load it carries;

5.26 x 10^(5)J = 1000 x 9.8 x h

So, h = [5.26 x 10^(5)]/(9.8 x 1000) = 52.7m

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz

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