A ball is projected upwards from the top of a tower with a velocity 50ms- 1 making an angle 30° with the horizontal. The height of tower is 70m . After how many seconds from the instant of throwing, will the ball reach the ground. ( g=10ms- 2 )

Question

A ball is projected upwards from the top of a tower with a velocity 50ms- 1 making an angle 30° with the horizontal. The height of tower is 70m . After how many seconds from the instant of throwing, will the ball reach the ground. ( g=10ms- 2 ) (A) 2s (B) 5s (C) 7s (D) 9s

Tardigrade Admin · Accepted Answer

Using s=ut+(1/2)at2 in vertical direction -70=(50 sin 30 ° )t+(1/2)(.-10.)t2 On solving this equation, we get t = 7 s

Q. A ball is projected upwards from the top of a tower with a velocity $50 m s^{- 1}$ making an angle $3 0^{\circ}$ with the horizontal. The height of tower is $70 m$ . After how many seconds from the instant of throwing, will the ball reach the ground. ( $g = 10 m s^{- 2}$ )

$2 s$

$5 s$

$7 s$

$9 s$

Using $s = u t + \frac{1}{2} a t^{2}$ in vertical direction
$- 70 = (50 s in 3 0^{\circ}) t + \frac{1}{2} (- 10) t^{2}$
On solving this equation, we get
t = 7 s

Q. A ball is projected upwards from the top of a tower with a velocity 50ms−1 making an angle 30∘ with the horizontal. The height of tower is 70m . After how many seconds from the instant of throwing, will the ball reach the ground. ( g=10ms−2 )

2s

5s

7s

9s