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5.Work, Energy, Power and Collision
medium
A body of mass $5\,kg$ is moving with a momentum of $10\,kg\,ms ^{-1}$. Now a force of $2\,N$ acts on the body in the direction of its motion for $5\,s$. The increase in the Kinetic energy of the body is $...........J$.
A
$30$
B
$29$
C
$28$
D
$27$
(JEE MAIN-2023)
Solution
Given
$M =5\,kg$
$P _{ i }=10\,kg\,m / s \text { (initial momentum) }$
$\text { Impulse }= F \Delta t =\Delta P = P _{ f }- P _{ i }$
$2 \times 5= P _{ f }-10$
$P _{ f }=20\,kg\,m / s \text { (final momentum) }$
$\text { Increase in } KE = KE _{ f }- KE _{ i }$
$=\frac{ P _{ f }^2}{2 m }-\frac{ P _{ i }^2}{2\,m }$
$=\frac{400}{2 \times 5}-\frac{100}{2 \times 5}=40-10=30\,J$
Standard 11
Physics
