Step 1: Identifying the error.
The sentence is talking about "one" of the friends, which is singular. Therefore, the verb "are" should be replaced with the singular form "is."
Step 2: Analyzing the Options.
- (A) A: This segment is correct. "One" is singular, so it requires a singular verb.
- (B) B: This segment has the error. "Are" is plural, but the subject "one" is singular. It should be "is."
- (C) C: This is also correct. The phrase "going to London next week" is grammatically fine.
- (D) no error: There is an error in the sentence, so this option is incorrect.
Step 3: Conclusion.
The error is in segment (B), where the verb should be "is" instead of "are."
A weight of $500\,$N is held on a smooth plane inclined at $30^\circ$ to the horizontal by a force $P$ acting at $30^\circ$ to the inclined plane as shown. Then the value of force $P$ is:
A steel wire of $20$ mm diameter is bent into a circular shape of $10$ m radius. If modulus of elasticity of wire is $2\times10^{5}\ \text{N/mm}^2$, then the maximum bending stress induced in wire is: