No. I do not agree with Stefan. Quite the contrary. I disagree
with his description of "<span>angle of incidence" as the angle between
the surface of the mirror and the incoming ray.
The correct description of "angle of incidence" is </span><span>the angle between
the NORMAL TO the surface of the mirror and the incoming ray.
Thus, the true angle of incidence is the complement of the angle that
Stefan calculates or measures.</span>
Answer:

Explanation:
Using the first law of thermodynamics:

Where
is the change in the internal energy of the system, in this case
,
is the heat tranferred, and
is the work,
with a negative sign since the work is done by the system.
From the previous equation we solve for heat, because it is the unknown variable in this problem

And replacing the known values:



The negative sign shows us that the heat is tranferred from the system into the surroundings.
Possibly, if you have list of densities and you have to match it. I can't think of any other scenarios in which it would be able to.
Hope I helped! :)
Answer:
m = 3 kg
The mass m is 3 kg
Explanation:
From the equations of motion;
s = 0.5(u+v)t
Making t thr subject of formula;
t = 2s/(u+v)
t = time taken
s = distance travelled during deceleration = 62.5 m
u = initial speed = 25 m/s
v = final velocity = 0
Substituting the given values;
t = (2×62.5)/(25+0)
t = 5
Since, t = 5 the acceleration during this period is;
acceleration a = ∆v/t = (v-u)/t
a = (25)/5
a = 5 m/s^2
Force F = mass × acceleration
F = ma
Making m the subject of formula;
m = F/a
net force F = 15.0N
Substituting the values
m = 15/5
m = 3 kg
The mass m is 3 kg