Question

a body is thrown with velocity of 49 m s^-1 at an angle of 30° with the horizontal, time required to attain maximum height is

(A) 5s (B) 4s (C) 3.5s (D)2.5s​

Answer 1

Given :

Initial velocity of body = 49m/s

Angle of projection = 30°

To Find :

Time taken by body to attain maximum height.

Solution :

❖ A body is said to be projectile if it is projected into space with some initial velocity and then it continues to move in a vertical plane such that its horizontal acceleration is zero and vertical downward acceleration is equal to g.

» Time taken by body to come back at ground is called time of flight.

$\sf:\implies\:T=\dfrac{2u\:sin\theta}{g}$

$\sf:\implies\:T=\dfrac{2(49)\:sin30^{\circ}}{9.8}$

$\sf:\implies\:T=\dfrac{98\:(1/2)}{9.8}$

$\sf:\implies\:T=\dfrac{10}{2}$

$\bf:\implies\:T=5\:s$

♦ Time taken by body to attain maximum height will be equal to the half of the time of flight.

➠ t = T/2

➠ t = 5/2

➠ t = 2.5 s