The Celsius scale (
).
In the Celsius temperature scale, the temperature at which water freezes is set conventionally at
, while the temperature at which the water boils is set at
. The Celsius degree is then defined as the unit corresponding to 1/100 of this time interval, between the temperature of freezing and boiling of the water.
Reflecting telescopes are popular because they are more durable than a refracting telescopes.
There is a difference between these two types of telescopes, reflecting telescopes worked by reflecting light, they are also known as reflector and refracting telescopes worked by refracting light and they are also known as reflactor.
Reflecting telescopes also provides a good focus.
Work done = force x distance = 40 x 2 = 80 Joules.
It stays constant, because it's using that energy to change state