A block of metal 4 kg is in rest on a frictionless surface. It was targeted by a jet releasing water of $2…

A block of metal 4 kg is in rest on a frictionless surface. It was targeted by a jet releasing water of $2 \mathrm{~kg} \mathrm{~s}^{-1}$ at a speed of $10 \mathrm{~ms}^{-1}$. The acceleration of the block is
  1. $10 \mathrm{~ms}^{-2}$
  2. $15 \mathrm{~ms}^{-2}$
  3. $20 \mathrm{~ms}^{-2}$
  4. $5 \mathrm{~ms}^{-2}$

Solution


$\mathrm{v}=10 \mathrm{~m} / \mathrm{s}, \frac{\mathrm{dm}}{\mathrm{dt}}=2 \mathrm{~kg} / \mathrm{s}$
$\therefore \quad$ Force applied by jet on the block is $\mathrm{F}=\mathrm{v} \cdot\left(\frac{\mathrm{dm}}{\mathrm{dt}}\right)=10 \times 2=20 \mathrm{~N}$
$\therefore \quad$ Acceleration of the block is
$\mathrm{a}=\frac{\mathrm{F}}{\mathrm{~m}}=\frac{20}{4}=5 \mathrm{~m} / \mathrm{s}^2$

Asked in: AP EAMCET 2024 (21 May Shift 2)

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