Question

Among the following, the weakest force is
1. gravitational force
2. electric force
3. nuclear force
4. magnetic force

Answer 1

Correct Answer - Option 1 : gravitational force

Concept:

• Force is a physical quantity that changes or tends to change the position, size, or direction of motion. 
• The SI unit of force is Newton. 
• Some of the examples of Forces are

Gravitational Force

• It is the force between two objects by virtue of their mass. 
• The planetary motions are based on gravitational force. 
• The Law of Gravitation was given by Sir Issac Newton. The force between two objects of mass m₁ and m₂ separated by distance r is given as

\(F =\frac{Gm_1m_2}{r^2}\)

G is a universal Gravitational Constant having the value 6.67 × 10 ^-11 N m² Kg ^-2

Electric Force

• It is the force acting between two charged particles. 
• It is given as 

\(F =\frac{kq_1q_2}{r^2}\)

Here, q₁ and q₂ are magnitudes of charges, r is the distance between them. The value of constant k is 9 × 10 ⁹ N m² C^-2

• We can see that k is too large compared to G. It signifies, the electric force is much larger when compared with Gravitational force in given conditions. 

Nuclear Forces

• The Nuclear force is the force that binds the nucleons (Protons and neutrons) together in the nucleus. 
• There are two types of Nuclear Force, strong and weak. 
• The strong nuclear force acts when the distance between nucleons is less than 10 ^-15 m or 1 fermimeter.  
• In that case, it is even stronger than electrostatic force.
• The weak nuclear force is weaker than the strong nuclear force but stronger than the gravitational force. 
• The force can be observed during the β decay of the nucleus. 

Magnetic Force

• It is the force that attracts magnetic substances.
• When a magnet is brought near iron nails, it attracts them.
• A small magnet can attract pins, which are held by the gravity of large earth. So, clearly, it is stronger than the gravitational force. 

Explanation:

So, we get the basic idea about the forces given and their relative strength. 

The following table signifies the strength of different forces. 

Force	Relative Strength
Gravitational Force	10 - 39
Electric Force	10 - 2
Strong Nuclear Force	10 -13
Weak Nuclear Force	1

Note: -The source of the above data is NCERT Textbook of class 11. 

So, the weakest force is gravitational force.