While a game is in progress, Jack has to run around the soccer field from corner to corner to relay a message to his coach. But during half-time Jack is able to run diagonally from one corner to the other.

u=13

v=30

s/t=u+1\2at

=13+431/2

=13+265.5

=278.5

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more

i think the answer is a, hope this : )

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.