Which describes the force between two magnets when their south poles are almost touching?
a. the poles strongly attract each other.
b. the poles weakly repel each other.
c. the poles strongly repel each other.
d. the poles weakly attract each other.

Explanation:

Decrease in kinetic energy of the ball

= 1/2 m ( v² - u² )

= 1/2 x .6 ( 8.3² - 7.1² )

= 5.544 J

This energy will be converted into potential energy

mgH = 5.544 ( H is maximum height attained )

H = 5.544 /( .6 x 9.8 )

= .942 m

= 94.2 cm

b ) In a ) we used the relation

mgH = 1/2 m ( v² - u² )

H =  ( 1/2g ) x ( v² - u² )

Here we see H or height attained does not depend upon mass as m cancels out on both sides.