-->

Motion In A Plane

Question
CBSEENPH11018541

A ball thrown up is caught by the thrower 4 s after start. What is the height to which the ball has risen?

Solution

Time of ascent = Time of descent. 
Therefore, 
t1 + t2 = 4
t2 + t2 = 4
This implies, 
t2 = 2 sec
Now, taking vertical downward motion of the ball from the highest point to surface of earth we have, 
u = 0, a = 10 m/s, t = 2 s, s = ? 
Now, using the formula,
                      s = ut + 1/2 at2
                         = space 0 space plus space 1 half straight x 10 space straight x space left parenthesis 2 right parenthesis squared 
                         = 20 m
This is the height to which the ball has risen.