Question

A happy graduate throws her cap into the air. It comes back to her hand (at the same height) in exactly 2.0 seconds. With what velocity did she originally throw the cap? Assume the acceleration due to gravity is -10 m s2 .

Answer 1

 $v_f=v_o-gt$

v_f=0

$v_o= g*t$ (1)

having into account that the total time spent in air till the cap came to her hands is Ttotal=2*t

where t is the time which the cap spent to reach the heighest point or the maximun height. so;

Ttotal=2second

t=1sec

we then replace t into the equation(1);

$v_o= (9,8)*(1s)= 9,8m/s$ 

this is the initial velocity with which the cap was thrown

Answer 2

the answer is B) 10 m/s