Question

A block of metal weighing 2 kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of 1 kg/sec and at a speed of 5 m/sec. The initial acceleration of the block will be –

• A. 2.5 m/s²
• B. 5.0 m/s²
• C. 10 m/s²
• D. 25 m/s²

Answer 1

Answer: (A)

2.5 m/s²

Answer 2

F = $\frac{dp}{dt}$ or ma = $\frac{dm}{dt}$ × v

or 2 × a = 1 × 5 ̃ a = 2.5 m/s