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Explain whyThe size of the needle of a syringe controls flow rate better than the thumb pressure exerted by a doctor while administering an injection. |
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Answer» The size of the needle controls the velocity of flow and the thumb pressure controls the pressure. According to Bernoulli’s equation: P + ρgh+ \(\frac{1}{2}\)ρv2 = constant we can note that the equation varies linearly with pressure, P but varies as the square of the velocity. Hence the contribution of velocity of flow is greater, due to which the needle has a better control over the flow. |
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