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1. Electric Charges and Fields
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A mass $m = 20\,g$ has a charge $q = 3.0\,mC$. It moves with a velocity of $20\,m/s$ and enters a region of electric field of $80\,N/C$ in the same direction as the velocity of the mass. The velocity of the mass after $3$ seconds in this region is.......$m/s$
A
$80$
B
$56$
C
$44$
D
$40$
Solution
(b) $a = \frac{{QE}}{m} = \frac{{3 \times {{10}^{ – 3}} \times 80}}{{20 \times {{10}^{ – 3}}}} = 12\,m/se{c^2}$
Hence $v = u + at$ $==>$ $v = 20 + 12 × 3 = 56\, m/s$.
Standard 12
Physics
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