Answer:
Explanation:
Let the vertical height by which it descends be h . Let it acquire velocity of v .
1/2 mv² = mgh
v² = 2gh
As it leaves the surface of sphere , reaction force of surface R = 0 , so
centripetal force = mg cosθ where θ is the angular displacement from the vertex .
mv² / r = mg cosθ
(m/r )x 2gh = mg cosθ
2h / r = cosθ
cosθ = (r-h) / r
2h / r = r-h / r
2h = r-h
3h = r
h = r / 3
Answer:

cubic metre or 1e-9
Explanation:
•By division. Number of cubic millimetre divided(/) by 1000000000, equal(=): Number of cubic metre.
•By multiplication. 83 mm3(s) * 1.0E-9 = 8.3E-8 m3(s)
Answer:
true,true,false
Explanation:
its false because if it is equal it would show an arrow pointing left and a 20 and the same for the right
Note that
1 J = 0.239 cal
By definition,
Work = Force x Distance
Therefore work done is
W = (1 N)*(2000 m) = 2000 J
In calories,
W = (2000 J)*(0.239 cal/J) = 478 cal
Answer: 478 calories
Radio waves have many uses—the category is divided into many subcategories, including microwaves and electromagnetic waves used for AM and FM radio, cellular telephones and TV.
The lowest commonly encountered radio frequencies are produced by high-voltage AC power transmission lines at frequencies of 50 or 60 Hz. These extremely long wavelength electromagnetic waves (about 6000 km) are one means of energy loss in long-distance power transmission.
Extremely low frequency (ELF) radio waves of about 1 kHz are used to communicate with submerged submarines. The ability of radio waves to penetrate salt water is related to their wavelength (much like ultrasound penetrating tissue)—the longer the wavelength, the farther they penetrate. Since salt water is a good conductor, radio waves are strongly absorbed by it; very long wavelengths are needed to reach a submarine under the surface.
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