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Force from the rate at which a jet or a stream of bullets delivers momentum

This type of question, asked 3 times: 29 Jun 2022, 28 Jul 2022, 11 Apr 2023. All 3 questions below, oldest first.

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  1. Question 1

    29 Jun 2022

    11
    A block of metal weighing 2 kg2\text{ }kg is resting on a frictionless plane (as shown in figure). It is struck by a jet releasing water at a rate of 1kgs−11kgs^{- 1} and at a speed of 10 ms−110{\text{ }ms}^{- 1}. Then, the initial acceleration of the block (in ms−2ms^{- 2}) will be:

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  2. Question 2

    28 Jul 2022

    93
    A pressure-pump has a horizontal tube of cross-sectional area 10 cm210{\text{ }cm}^{2} for the outflow of water at a speed of 20 m/s20\text{ }m/s. The force exerted on the vertical wall just in front of the tube which stops water horizontally flowing out of the tube, is: [given: density of water =1000 kg/m3= 1000\text{ }kg/m^{3} ]

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  3. Question 3

    11 Apr 2023

    19
    An average force of 125 N125\text{ }N is applied on a machine gun firing bullets each of mass 10 g10\text{ }g at the speed of 250 m/s250\text{ }m/s to keep it in position. The number of bullets fired per second by the machine gun is:

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