Question

Plz answer this .....do give a step by step explanation ​

Answer 1

Answer:

The two balls meet at height h=15.1,

Explanation:

Let h is the height of point where two balls meet.

In downward motion,

u=20m\s,a=9.8m/s2,s=40-h.

s=ut+1/2at2

40-h=20(t)+1/2×9.8t2

40-h=20t+4.9t2

40-20t-4.9t2=h----(1)

In upward motion,

u=20m/s,a=-9.8m/s2,s=h.

s=ut+1/2at2

h=20t+1/2×-9.8t2

h=20t-4.9t2--------(2)

compare (1)&(2),

40-20t-4.9t2=20t-4.9t2

40=20t+20t

40=40t

*t=40/40

t=1s.

put t=1s in(2)

h=20(1)-4.9×(1)2

h=20-4.9

h=15.1m.