Our values can be defined like this,



The problem can be solved for part A, through the Work Theorem that says the following,

Where
KE = Kinetic energy,
Given things like that and replacing we have that the work is given by
W = Fd
and kinetic energy by

So,

Clearing F,

Replacing the values


B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.
D only kinetic energt because if it had heluim or any thing jt will float up
Answer:
f =-20 cm
Explanation:
Given that,
The magnification of a spherical mirror, m = -1
The image distance, v = 40 cm (for negative magnification)
The magnification of a concave mirror is negative. The mirror showing -1 magnification is a concave mirror.
Let f be the focal length of the mirror. We know that,

Object distance, u = -40 cm
Using mirror's formula i.e.

So, the focal length of the mirror is 20 cm.
Mass and gravitational field