Question

Read the passage carefully and give the answers of the following question:
In a laboratory experiment on friction, a block of weight $135N$ lying on a rough horizontal table is pulled by a horizontal wire. The pull $\left(P\right)$ gradually increases until the block begins to move and continues to increase thereafter. Given figure shows a graph of the friction force $\left(f\right)$ on this block as a function of the pull $\left(P\right)$.
The region of the graph where Static friction occurs is from

• A. $P=0N\text{to}P=100N$
• B. $P=0N\text{to}P=75N$
• C. $P=75N\text{to}P=100N$
• D. Only at $P=75N$

Answer 1

The correct option is B $P=0N\text{to}P=75N$


When a force is applied to an object lying on a rough surface, a resisting force comes into existence which is static friction and it is a self adjusting force as it increases with applied force till it reaches the value of limiting friction which is the maximum force it can resist. Static friction region where friction force is directly proportional to the applied force. Hence the range of static friction is from $P=0N$ to $P=75N$ i.e., option (2).