Electrostatics Question 370
Question: A mass $ m=20g $ has a charge $ q=3.0mC $ . It moves with a velocity of $ 20m/s $ and enters a region of electric field of $ 80N/C $ in the same direction as the velocity of the mass. The velocity of the mass after 3 seconds in this region is
Options:
A) $ 80m/s $
B) $ 56m/s $
C) $ 44m/s $
D) $ 40m/s $
Show Answer
Answer:
Correct Answer: B
Solution:
$ a=\frac{QE}{m}=\frac{3\times {{10}^{-3}}\times 80}{20\times {{10}^{-3}}}=12m/sec^{2} $
Hence v = u + at therefore v = 20 + 12x 3 = 56 m/s.
