An atom is the smallest part of an element
Answer:

Explanation:
Given
first stone mass is m
second stone mass is 6 m
distance traveled by first stone in 430 ms



Distance traveled by stone 2 in t=430-59=371 ms



velocity of first stone after t=0.43 s


velocity of second stone after t=0.371 s


Position of Center of mass of system



Velocity of COM



At the highest point: kinetic energy is 0 due to the speed is 0
So the total mechanical energy is 20
Assume no frictions present, then the mechanical energy is conserved
So at the lowest point, kinetic energy = mechanical energy - potential energy
Answer will be 20 - 0.5 = 19.5 J