Answer:
B
Explanation:
Reason is that the suitcase is exerted downward and when it moves downward the equation is mgsin tita
The net force is the 10N force and its direction is towards F2 force.
<h3>What is resultant force?</h3>
The resultant force or the net force is the actual force that acts on a body. We are told that the two forces act in opposite directions hence the net force is F2 - F1 = 30 N - 20 N = 10 N.
ii) The direction of this net force is going to be towards the 30N force.
iii) If the body does not move under the application of these forces then the F1 force must be reinforced by another force which balances it against the F2 force.
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Answer:

Explanation:
According to the Coulomb's law, the magnitude of the electrostatic force between two static point charges
and
, separated by a distance
, is given by

where k is the Coulomb's constant.
Initially,

The negative sign is taken with force F because the force is attractive.
Therefore, the initial electrostatic force between the charges is given by

Now, the objects are then brought into contact, so the net charge is shared equally, and then they are returned to their initial positions.
The force is now repulsive, therefore, 
The new charges on the two objects are

The new force is given by

Using (1),



Using (1),
When
,

When
,

Since, 
Therefore, 