The answer is a.12.5kg because i just did the test and it was correct.
hope this helps
The question ask to calculate and choose among the following is the distance of the microphone from the left - most speaker in order to pick up the loudest sound and the best answer would be letter C. I hope you are satisfied with my answer and feel free to ask for more if you have questions and further clarifications
Answer:
Explanation:
Given
Object is thrown with a velocity of 
Acceleration due to gravity is -g (i.e. acting downward)
Vertical distance traveled by object is given by
where v=final velocity
u=initial velocity
a=acceleration
s=displacement
at maximum height final velocity is zero


time taken to reach maximum height
using
v=u+at
0=9-gt
