Question

17. A ball is projected with velocity 10 m/sec at angle of 30° with the horizontal surface. The time taken by
ball to reach the ground is
a) 1 sec
b) 2 sec
c) 3 sec
d) 4 sec
e) 5 sec​

Answer 1

Answer:

Ans is 2 sec. Thanks

Explanation:

The ball's vertical position in the air is given by

y=10\cos30^\circ\,t-\dfracg2t^2y=10cos30

∘

t−\dfracg2t

2

and it will reach the ground at tt for which y=0y=0 :

0=5\sqrt3\,t-5t^2=5t(\sqrt 3-t)\implies t=\sqrt3\approx1.730=5

3

t−5t

2

=5t(

3

−t)⟹t=

3

≈1.73