Answer to Question #206828 in Mechanical Engineering for Rodel

Question

A projectile is fired at the top of a building at an angle of 20° below the horizontal. If the muzzle velocity of the projectile is 8 m/s, how high is the building if the projectile reaches the ground after 3sec. 

Answer 1

The equation to solve for time of the freight is a quadratic equation and is given as follows for object thrown at an angle below the horizontal.

$0.5gT^2+(usin\theta) T-h=0$

u, T and angle are given in the question. The same are substituted to obtain height of the building.

$h= 0.5gT^2+(usin\theta) T\newline h=0.5\times9.8\times3^2+8\times sin20 \times3\newline h= 52.31m$