1.

from the top of a tower of height 40m a ball is projected upward with a speedof 20m/sec at an elevation of 30degrees . the ratio of the total time taken by the ball to hit the ground to its time of flight (time taken to come back to the point of projection is g=10m/s

Answer»


Time TAKEN to reach maximum height in a horizontal projection :

H = 20²sin²30° / 2 × 10

H = (400 × 0.25) / 20 = 5m

TOTAL height is :

5 + 40 = 45 m

Time of flight = (2 × 20 × SIN 30) / 10 = 2 seconds

Time of FREE fall is √(2 × 45)/10 = √9 = 3 seconds.

The total time taken to reach the ground is thus :

1 + 3 = 4 Seconds

The ratio is thus :

4 : 2


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