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4-1.Newton's Laws of Motion
medium
If impulse $I$ varies with time $t$ as $I\left( kg ms ^{-1}\right)=20 t^2-40 t$. The change in momentum is minimum at ........... $s$
A$t=2$
B$t=1$
C$t=\frac{1}{2}$
D$t=\frac{3}{2}$
Solution
(b)
The definition of impulse, $I = F d t = m \frac{ dv }{ dt } dt = mdv =$ change in momentum. Thus, $I=20 t^2-40\,t$
For minimum of impulse, $\frac{ dI }{ dt }=0$ or $40\,t -40=0$ or $t =1\,s$
The definition of impulse, $I = F d t = m \frac{ dv }{ dt } dt = mdv =$ change in momentum. Thus, $I=20 t^2-40\,t$
For minimum of impulse, $\frac{ dI }{ dt }=0$ or $40\,t -40=0$ or $t =1\,s$
Standard 11
Physics
