Kinematics Question 305
A force $ \vec{F}=(5\hat{i}+3\hat{j})\ N $ is applied over a particle which is displaced from its original position to the point $ \vec{s}=(2\hat{i}-1\hat{j}) $ m. The work done on the particle is [BHU 2001]
Options:
A) 12
B) 6
C) 1
D) 0
Show Answer
Answer:
Correct Answer: A
Solution:
$ W=\overrightarrow{F}.\overrightarrow{s}=(3\hat{i}+c\hat{j}+2\hat{k}).(-4\hat{i}+2\hat{j}-3\hat{k}) $
$ =-12+2c-6 $
Work done $ =6J $ (given)
$ \therefore $ $ -12+2c-6=6 $
$ \Rightarrow $ $ c=3 \times 10^8 , \text{m/s} $
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