Answer:
distance between the dime and the mirror, u = 0.30 m
Given:
Radius of curvature, r = 0.40 m
magnification, m = - 2 (since,inverted image)
Solution:
Focal length is half the radius of curvature, f = 
f = 
Now,
m = - 
- 2 = -
= 2 (2)
Now, by lens maker formula:


v =
(3)
From eqn (2):
v = 2u
put v = 2u in eqn (3):
2u = 
2 = 
2(u - 0.20) = 0.20
u = 0.30 m
The first thing you should do is calculate the work done when climbing the stairs. This work by definition will be given by:
W = F * d
W = (m * g) * (d)
W = ((71) * (9.8)) * (3) = 2087.4J
Then, you can calculate the power that in this case is given by
P = W / t
P = (2087.4) / (10) = 208.74W
To have the result in HP we use the fact that 1HP = 746W
P = (208.74) / (746)
P = 0.28 HP
answer
the power you produce in running up a flight of stairs is 0.28 HP
The first law of thermodynamics is expresses by
D. ΔU=Q-W
which means change in internal energy of system = Heat added to system minus work done by the system
All are expressed in Joules.
This law is based on principle of conservation of energy.