Answer:
Explanation:
A magnet has a magnetic field around it which originates at the north pole and enters through the south pole.
In a magnet, like poles will repel each other and unlike poles will attract.
- The north pole of one magnet will repel another north pole of another magnet.
- North pole of one magnet will attract the south pole of another magnet.
- This is the law of attraction and repulsion of magnet.
<span>e=ca{\displaystyle e={\frac {c}{a}}}.</span>
Explanation: Electrostatic force is directly related to the charge of each object. So if the charge of one object is doubled, then the force will become two times greater.
Here when an object is placed on the level floor then in that case there are two forces on the object
1). Weight of object downwards (mg)
2). Normal force due to floor which will counterbalance the weight (N)
so when no force is applied on the box at that time normal force is counter balanced by weight.
Now here it is given that A person tried to lift the box upwards
So now there are two forces on the box
1). Applied force of person
2). Normal force due to ground
So now these two forces will counter balance the weight of the crate
So we can write an equation for force balance like

given that

here
m = 30 kg and
g = acceleration due to gravity = 10 m/s^2

now from above equation


So force applied by the person must be 150 N