Answer: Mechanical waves carry energy through a medium; electromagnetic waves carry energy through media and space.
Explanation:
<u>The waves which require medium to travel are known as mechanical waves. </u>The waves carry energy forward by compression and rarefaction that is by changing density /pressure of medium particles.
<u>Electromagnetic waves can transfer energy through space as well as medium. </u>In an electromagnetic wave, electric field generates magnetic field and magnetic field generates electric field. Electric field and magnetic field are perpendicular to each other and to the direction of motion.
We shall convert all of the densities to lbs/gal, so the product of
BTU/lbs and lbs/gal gives us the basis of comparison, which was "ratio of energy to volume".
grams / ml x 1 lbs/454 grams → 1 lbs/ 454 ml
1 lbs/454 ml x 3785.41 ml/gal → 3785.41 lbs/454gal
Conversion of g/ml = 8.34 lbs/gal
Looking at each fuel:
Kerosene:
18,500 x (8.34 x 0.82) = 126,517 BTU/gal
Gasoline:
20,900 x (8.34 x 0.737) = 128,463 BTU/gal
Ethanol:
11,500 x (8.34 x 0.789) = 75,673 BTU/gal
Hydrogen:
61,000 x (8.34 x 0.071) = 36,120 BTU/gal
The best fuel in terms of energy to volume ratio is Gasoline.
Gallons required:
BTU needed / BTU per gallon
= 85.2 x 10⁹ / 128,463
= 6.6 x 10⁵ gallons
I think it is June. June is the longest day/
Answer:
Explanation:
radius of circle r = 0.9 m.
(a ) In a motion on circular path , work done is zero because force ( centripetal force ) acts perpendicular to displacement .
( b )
Tension in string T = m ω²r
Putting the values
60 = .072 x ω² x 0.9
ω² = 926
ω = 30.4 rad /s
angle made in 20 revolutions θ = 20 x 2π = 126.6 rad
time taken = θ / ω
= 126.6 / 30.4
= 4.16 s .