A 10kg mass is moving to the right with a velocity of 15 m/s. A 13kg mass is moving to the left with a velocity of 6.0 m/s. Assuming that these two
masses have a head on collision and stick together, what would be the
final velocity and to what direction? *

M1u1+(-m2u2) = (m1+m2) V. By using this equation you can find the final velocity of that. It would be 3.13ms-1. And the direction is right side.

v 154.9= 0.9 length length s little over 154.9cm

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force