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4.1 , newtons laws of motion — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics4.1 , newtons laws of motion1 Mark
MCQ
Consider the following statement: When jumping from some height, you should bend your knees as you come to rest, instead of keeping your legs stiff. Which of the following relations can be useful in explaining the statement
  • A
    $\Delta \overrightarrow {{P_1}} = - \Delta \overrightarrow {{P_2}} $
  • B
    $\Delta E = - \Delta (PE + KE) = 0$
  • ✓
    $\overrightarrow F \Delta t = m\Delta \overrightarrow v $
  • D
    $\Delta \overrightarrow x \propto \Delta \overrightarrow F $
✓

Answer

Correct option: C.
$\overrightarrow F \Delta t = m\Delta \overrightarrow v $
c
(c)$\overrightarrow F \Delta t = m\Delta \overrightarrow v $  $⇒$  $F = \frac{{m\Delta \overrightarrow v }}{t}$

By doing so time of change in momentum increases and impulsive force on knees decreases.

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