A fixed incident ray strikes plane-mirror at an angle of incidence of 20°. If the mirror is now rotated through angle of 30°, calculate the angle between
the incident and reflected rays.​

as technology advances, new experiments often expose problems in accepted theories. c

hope i

-lavira: )

heats surface water up

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.