Answer:
2.63 x 10^18
Explanation:
A = 1 cm^2 = 1 x 10^-4 m^2
λ = 10,000 nm = 10,000 x 10^-9 m = 10^-5 m
T = 37 degree C = 37 + 273 = 310 k
Energy of each photon = h c / λ
where, h is the Plank's constant and c be the velocity of light
Energy of each photon = (6.63 x 10^-34 x 3 x 10^8) / 10^-5 = 1.989 x 10^-20 J
Energy radiated per unit time = σ A T^4
Where, σ is Stefan's constant
Energy radiated per unit time = 5.67 x 10^-8 x 10^-4 x 310^4 = 0.05236 J
Number of photons per second = Energy radiated per unit time / Energy of
each photon
Number of photons per second = 0.05236 / (1.989 x 10^-20) = 2.63 x 10^18
Answer:
energy can move from one location to another, the particles of matter in the medium return to their fixed position. A wave transports its energy without transporting matter.
The car travels a distance <em>d</em> from rest with acceleration <em>a</em> after time <em>t</em> of
<em>d</em> = 1/2 <em>a</em> <em>t</em>²
It covers 69 m with 2.8 m/s² acceleration, so that
69 m = 1/2 (2.8 m/s²) <em>t</em>²
<em>t</em>² = 2 (69 m) / (2.8 m/s²)
<em>t</em> ≈ 7.02 s
where we take the positive square root because we're talking about time *after* the car begins accelerating.
Use the formular d = v x t
d = 2m
v= 100m/s
t= d / v
= 2 / 100
= 0.02sec
Answer:
Explanation:
The strength of the gravitational field at the surface of a planet is given by
(1)
where
G is the gravitational constant
M is the mass of the planet
R is the radius of the planet
For the Earth:
For the unknown planet,
Substituting into the eq.(1), we find the gravitational acceleration of planet X relative to that of the Earth:
And substituting g = 9.8 m/s^2,
