Q. A force $\vec F=2\hat i+b\hat j+\hat k$ is applied on a particle and it undergoes a displacement $\hat i-2\hat j-\hat k$. What will be the value of $b$, if work done on the particle is zero.
A) 0
B) $\frac12$
C) 2
D) $\frac13$
Explanation
[Solution by Dr. Abubacker] $W=\vec F\cdot\vec d=2-2b-1=0\Rightarrow b=\frac12$. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.