Answer with Explanation:
We are given that
Force acts on a pebble=
N
Position vector=
m
a.We have to find the resulting torque on the pebble about origin.
Torque=
Substitute the values then we get

Torque=
N-m
By using 
b.

Torque about point (2,0,-3)

N-m
Answer:
The trouble that the most recent experiment, Borexino, have to overcome was that
neutrinos hardly interact with matter and so radioactive decay of ant material inside the detector could look exactly like a neutrino interaction too
Complete Question
The complete question is shown on the first uploaded image
Answer:
Explanation:
From the question we are told that
The tension is
The length of the wire is 
The mass is 
Generally the frequency is mathematically represented as

=> 
=> 