Question

an object is projected vertically up from the top of a tower of height 58.8 m with an initial velocity 4.9m/s calculate the time of flight of the object
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Answer 1

ans = 4 sec

explanation

first of all use

v=u - gt

0=4.9 - 9.8*t

t1 =0.5 sec

now find the maximum height from tower

$h = \frac{u {}^{2} }{2g}$

h=1.225

from this point calculate total height from ground i.e

H= 58.8+1.225

=60

now use

$h = \frac{1}{2} \times gt {}^{2}$

t2 =3.5 sec

hence

total time taken = t1 +t2

0.5+3.5

4 second

Answer 2

Explanation:

ans = 4 sec

explanation

first of all use

v=u-gt

0=4.9-9.8*t

t1=0.5 sec

now find the maximum height from tower

h u2 29

h=1.225

from this point calculate total height from ground i.e

H=58.8+1.225

=60

now use

h = 1 x gt2

t2 =3.5 sec

hence

total time taken = t1 +t2

0.5+3.5

4 second