A ball dropped from rest falls freely until it hits the ground with a speed of 18 meters per second. How long did it take for the ball to reach the ground?

1.8 secs

Explanation:

u= 0

v= 18m/s^2

t= ?

v= u +at

18= 0 + 10×t

18= 10t

t= 18/10

t= 1.8 secs

Hence it will take the ball 1.8 secs to reach the ground

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s