2. A boy walks 3 miles north then turns around and walks on the same path south for 2.1 miles. What is the boy's displacement?

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach