Question

A block of weight $4\,kg$ is resting on a smooth horizontal plane. If it is struck by a jet of water at the rate of $2\, kgs^{-1}$ and at the speed of $10\, ms^{-1}$, then the initial acceleration of the block is

• A. $15\, ms^{-2}$
• B. $10\, ms^{-2}$
• C. $2.5\, ms^{-2}$
• D. $1\, ms^{-2}$
• E. $5 \,ms^{-2}$

Answer 1

Answer: (E)

$F=\frac{d m}{d t} \cdot V=2 \times 10$
The initial acceleration of block
$a =\frac{F}{m}=\frac{2 kgs ^{-1} \times 10 ms ^{-2}}{4} $
$=\frac{20}{4}=5\,ms ^{-2}$