Answer:
Of the three stars in the system, the dimmest - called Proxima Centauri - is actually the nearest star to the Sun. The two bright stars, called Alpha Centauri A and B form a close binary system; they are separated by only 23 times the Earth - Sun distance.
Answer:
Explanation:
The equivalent resistance for three resistors connected in parallel is given as
(1/R)=(1/R₁)+(1/R₂)+(1/R₃)
now we.need to.insert the value of 3 resistances but only 2 are given in the question.
Answer:
Explanation:
(ΔK + ΔUg + ΔUs + ΔEch + ΔEth = W)
ΔK is increase in kinetic energy . As the athelete is lifting the barbell at constant speed change in kinetic energy is zero .
ΔK = 0
ΔUg is change in potential energy . It will be positive as weight is being lifted so its potential energy is increasing .
ΔUg = positive
ΔUs is change in the potential energy of sportsperson . It is zero since there is no change in the height of athlete .
ΔUs = 0
ΔEth is change in the energy of earth . Here earth is doing negative work . It is so because it is exerting force downwards and displacement is upwards . Hence it is doing negative work . Hence
ΔEth = negative .
b )
work done by athlete
= 400 x 2 = 800 J
energy output = 800 J
c )
It is 25% of metabolic energy output of his body
so metalic energy output of body
= 4x 800 J .
3200 J
power = energy output / time
= 3200 / 1.6
= 2000 W .
d )
1 ) Since he is doing same amount of work , his metabolic energy output is same as that in earlier case .
2 ) Since he is doing the same exercise in less time so his power is increased . Hence in the second day his power is more .
The thing that pushes the object up while it is falling is air. This force is known as "air resistance".
Answer: 9.98 *10^-19 J
Explanation: In order to explain this probelm we have to consider the balance enegy for photoelectric effect.
h*f-W=Ek where h is the Planck constant and W the work function and Ek the kinetic energy. f is the frequency of light.
W=h*f-Ek=6.62*10^-34*2.4*10^15-5.9*10^-19=9.98*10^-19J
