Explanation:
It is given that,
Force, 
Position vector, 
(a) The torque on the particle about the origin is given by :

(b) To find the angle between r and F use dot product formula as :

Hence, this is the required solution.
Answer:

Explanation:
A right triangle is formed, in which the vertical elevation is the opposite cathetus and the horizontal distance is the adjacent cathetus, since we know these two values, we can calculate the angle of inclination using the definition of tangent:

Answer:
Found in the nucleus, Has mass of one amu
The two forces should be equal therefore:
2.10 * Fa = Fa + 2 * F * cos 18
simplifying the right side:
2.10 * Fa = Fa + 1.902 * F
1.10 Fa = 1.902 F
<span>F / Fa = 0.578</span>