Answer :
The time difference between their landing is 2.04 seconds.
Time of difference of the two balls
The ball thrown vertical upwards will take double of the time taken by the ball thrown vertically downwards.
Time difference, = 2t - t = t
t = √(2h/g)
where;
- h is the height of fall
- g is acceleration due to gravity
Apply the principle of conservation of energy;
¹/₂mv² = mgh
h = v²/2g
where;
- v is speed of the ball
h = (20²)/(2 x 9.8)
h = 20.41 m
Time of motion
t = √(2 x 20.41 / 9.8)
t = 2.04 s
Thus, the time difference between their landing is 2.04 seconds.
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