Answer: Pascal’s principle (apex)
Hope this helps you out!
We use the law of Cosines, resultant force

Here,
and
are forces acting at angle
with each other.
Given
,
and
.
Substituting these given values in above formula we get
.
Thus, the resultant force is 156 N.
It is given that the height of the tower is

The uncertainty the measurement of this height is

Drop time is measured as:

The uncertainty in measurement of time is:

Using the equation of motion:
where,
is the distance covered,
is the initial velocity,
is the acceleration and
is the time.
(because canon ball is in free fall). we need to calculate the value of a=g.


The uncertainty in this value is given by:

Substitute the values:

Answer:
36.25 N
Explanation:
The magnitude of the electrostatic force between two charges is given by Coulomb's law:
where:
is the Coulomb's constant
are the magnitude of the two charges
r is the separation between the two charges
Moreover:
- The force is repulsive if the two charges have same sign
- The force is attractive if the two charges have opposite sign
In this problem, we have 3 charges:
is the charge located at 
is the charge located at 
is the charge located at 
The force between charge 1 and charge 3 is:

And since the two charges have opposite sign, the force is attractive, so the force on charge 3 is to the right (towards charge 1).
The force between charge 2 and charge 3 is:

And since the two charges have same sign, the force is repulsive, so the force on charge 3 is to the right (away from charge 2).
So the two forces on charge 3 have same direction (to the right), so the net force is the sum of the two forces:
