Answer:
3.066×10^21 photons/(s.m^2)
Explanation:
The power per area is:
Power/A = (# of photons /t /A)×(energy / photon)
E/photons = h×c/(λ)
photons /t /A = (Power/A)×λ /(h×c)
photons /t /A = (P/A)×λ/(hc)
photons /t /A = (680)×(678×10^-9)/(6.63×10^-34)×(3×10^-8)
= 3.066×10^21
Therefore, the number of photons per second per square meter 3.066×10^21 photons/(s.m^2).
Answer:
Earth's Tilt and The Seasons. Earth, like all of the planets in the Solar System, travels around the Sun. One complete orbit of the Sun is known as a year and it takes Earth 365 days, 5 hours, 48 minutes and 46 seconds to complete an orbit. The changing seasons are caused by the fact that Earth is tilted. please vote me brainliest i can't message no one cuz i haven't got enough points i'm desperate.
Explanation:
Answer:
D)Not enough information
Explanation:
According to Pascal's principle, the pressure exerted on the two pistons is equal:
Pressure is given by the ratio between force F and area A, so we can write
The force exerted on each piston is just equal to the weight of the corresponding mass: 
, where m is the mass and g is the gravitational acceleration. So the equation becomes
Now we can rewrite the mass as the product of volume, V, times density, d:
We also know that 
So we can further re-arrange the equation (and simplify g as well):
We are also told that block B has bigger volume than block A: 
. However, this information is not enough to allow us to say if the fraction on the right is greater than 1 or smaller than 1: therefore, we cannot conclude anything about the densities of the two objects.
Answer:
The wave speed is calculated below:
Explanation:
Given,
number of waves passed per minute = 8
time period = 1 minute = 60 s
distance between successive wave crests = 20 m
waves passing interval per second = 
Now,
wave speed = 20 m ×
= 
m/s
= 2.67 m/s
Hence the wave speed is 2.67 m/s.
