Question

A ball is projected upward from the top of the tower with a velocity of 50 m/s making an angle of 30 with the horizontal .The height of the tower is 70 m after how much

Answer 1

Answer:

the answer of the question is 6.33

Answer 2

Complete Question: A ball is projected upward from the top of the tower with a velocity of 50 m/s making an angle of 30 with the horizontal .The height of the tower is 70 m. After how many seconds the ball will strike the ground?

Answer:

Ball Strikes after t = 7 s

Explanation:

Given;-

              v = 50 m/s ( velocity of ball projected upwards )

      ∅(let) = 30 degree ( angle of projection )

              h = 70 m ( height of the tower )

Now, finding components of V;

             Vx = u cos ∅

             Vx = 50 × cos 30

             Vx = 50 × √3/ 2

             Vx = 25√3 m/s

Also,      Vy = u sin ∅

             Vy = 50 × sin 30

             Vy = 50 × 1/2

             Vy = 25 m/s

Now, finding time of flight; ( assuming upward direction -ve and downward direction as +ve )

             S = ut + 1/2 at²

           70 = -25t + 1/2 × 10 × t²

           70 = - 25t + 5t²

           5t² - 25t - 70 = 0

             t² - 5t - 14 = 0

          t² - 7t + 2t - 14 = 0

         t ( t-7 ) + 2( t-7) = 0

        t = +7 , or t = - 2

So,   t = 7 s

Therefore, the ball will strike the ground after 7 seconds.