Question

A rock is projected from the edge of the top of a building with an initial velocity of 12.2 m/s at an angle of 73° above the horizontal. The rock strikes the ground a horizontal distance of 25 m from the base of the building. Assume that the ground is level and that the side of the building is vertical. What is the time?

Answer 1

Answer:

7 s

Explanation:

u = Initial velocity of rock = 12.2 m/s

$\theta$ = Angle of throw = $73^{\circ}$

x = Displacement in x direction = 25 m

Displacement in x direction is given by

$x=u\cos\theta t\\\Rightarrow t=\dfrac{x}{u\cos\theta}\\\Rightarrow t=\dfrac{25}{12.2\times \cos73^{\circ}}\\\Rightarrow t=7\ \text{s}$

Time taken to reach the ground is 7 s.