Block $A$ of mass $2 \,kg$ is placed over block $B$ of mass $8 \,kg$. The combination is placed over a rough horizontal surface. Coefficient of friction between $B$ and the floor is $0.5$. Coefficient of friction between $A$ and $B$ is $0.4$. A horizontal force of $10\, N$ is applied on block $B$. The force of friction between $A$ and $B$ is $(g = 10\, m\,s^{-2})$
- 100 N
- 40 N
- 50 N
- zero
The Correct Option is D
Solution and Explanation
Friction between surface and combination of $A$ and $B$
$F =\mu R$
$=0.5 \times 10 \times 10=50\, N$
Here applied force on box $B$ is $10\, N$ that is less than $50\, N$. So the system will be in rest because of this there is no friction between blocks $A$ and $B$.
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Concepts Used:
Laws of Motion
The laws of motion, which are the keystone of classical mechanics, are three statements that defined the relationships between the forces acting on a body and its motion. They were first disclosed by English physicist and mathematician Isaac Newton.
Newton’s First Law of Motion
Newton’s 1st law states that a body at rest or uniform motion will continue to be at rest or uniform motion until and unless a net external force acts on it.
Newton’s Second Law of Motion
Newton's 2nd law of motion deals with the relation between force and acceleration. According to the second law of motion, the acceleration of an object as built by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Newton’s Third Law of Motion
Newton's 3rd law of motion states when a body applies a force on another body that there is an equal and opposite reaction for every action.