Physics 2D motion problem

Question

While standing on the roof of a building, a child tosses a tennis ball with an initial speed of 10 m/s at an angle of 40° below the horizontal. The ball lands on the ground 3.3 s later. How tall is the building?

Answer 1

The initial velocity of the ball is 10 m/s

The angle made by the ball when it is tossed is ø = 40º below the horizontal 

The time taken by the ball to reach ground is t = 3.3 s

The height of the building can be measured by using below the formula

Where g is the gravitational constant ( g = 9.8 m/s² )

u is initial velocity component  40º below the horizontal = u sinø

 

So the height of building is 74.573 m