Question

A football is kicked at an 50 degree angle to the horizontal , travels a horizontal distance of 20m before hitting the ground. what is the initial speed?
please tell me how you would do this

Answer 1

Wind resistance is not a factor in this question as we haven't done that yet.

Answer 2

let u be the initial velocity , devide it into two component x and y
the angle is 50 degree given
so u in x direction = u cos50
in y direction = u sine50
time period = t= (2 u sine50)/g and
horizontal distance = u cos50 * t ( acceleration in x direction is zero)
by putting the value of t in above eqn yuou will get
s=ucos50* (2 u sine50)/g
20 g = 2 u^2 cos50 * sine50
from here u can get the value of u which is initial velocity....