Answer: because the ice was cold, and it melted in the tea. So the tea is now cooler.
Explanation:
Answer:
3.75 hours
Explanation:
By 
where v is the velocity (or speed in this case)
d is the distance travelled
t is the time taken

Therefore it takes 3.75 hours for the bus to travel 150 km and 40 km/hr.
Answer:
The sun looks bigger than other stars because it is closer to the Earth, distance makes it look larger
Answer:
Explanation:
The energy of a photon is given by the equation
, where h is the <em>Planck constant</em> and f the frequency of the photon. Thus, N photons of frequency f will give an energy of
.
We also know that frequency and wavelength are related by
, so we have
, where c is the <em>speed of light</em>.
We will want the number of photons, so we can write

We need to know then how much energy do we have to calculate N. The equation of power is
, so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be
.
Putting this paragraph in equations:
.
And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables:
