Arock is shot from a catapult at the top of a mountain a height h above a level plain below. the rock is fired at an angle θ above the horizontal and with an initial vi.(a)find a symbolic expression in terms of the variables vi, g, and θ for the time at which the rock reaches its maximum height.

Explanation:

Let the time taken by the shot to reach to maximum height is t.

initial velocity, vi

angle of projection, θ

Acceleration, g

At maximum height, the vertical component of velocity is zero.

use first equation of motion in vertical motion

grav forces affect all objects magnetic forces affect magnetic objects and electric currents

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement