Work is done. work=forcexdisplacement. the ice skater glides 2 meters (displacement), so yes.
Answer:
If efficiency is .22 then W = .22 * Q where Q is the heat input
Heat Input Q = 2510 / .22 = 11,400 J
Heat rejected = 11.400 - 2510 = 8900 J of heat wasted
Also, 8900 J / (4.19 J / cal) = 2120 cal
Answer:
Q = 2.95*10^5 kJ
Explanation:
In order to calculate the energy required to melt the cooper, you first calculate the energy required to reach the boiling temperature. You use the following formula:
(1)
m: mass of cooper = 540 kg
c: specific heat of cooper = 390 J/kg°C
Tb: boiling temperature of cooper = 1080°C
T1: initial temperature of cooper = 20°C
You replace the values of the parameters in the equation (1):

Next, you calculate the energy required to melt the cooper by using the following formula:
(2)
Lf: melting constant of cooper = 134000J/kg

Finally, the total amount of energy required to melt the cooper from a temperature of 20°C is the sum of Q1 and Q2:

The total energy required is 2.95*10^5 kJ
When light moves from a medium with higher refractive index to a medium with lower refractive index, the critical angle is the angle above which there is no refracted light, and all the light is reflected. The value of this angle is given by

where n2 and n1 are the refractive indices of the second and first medium, respectively.
In the first part of the problem, light moves from glass to air (

) and the critical angle is

. This means that we can find the refractive index of glass by re-arranging the previous formula:

Now the glass is put into water, whose refractive index is

. If light moves from glass to water, the new critical angle will be
The force of gravity is the
force with which massively large objects such as the earth attracts another
object towards itself. All objects of the earth exert a gravity that is
directed towards the center of the earth. Therefore, the force of gravity of
the earth is equal to the mass of the object times acceleration due to gravity and also equal to the weight of the object.
F = ma
since F = W
W = ma