Correct Answer - Option 4 : 2 sec
CONCEPT:
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Newton's Second Law of Motion: It says that the net external force on a system or body is equal to the change in momentum of the system or body divided by the time over which it changes.
Mathematically:
\(F_{ext} = {Δ p \over Δ t}\)
where Fext is the external force on the system, Δp is the change in momentum, and Δt is the change in time.
CALCULATION:
Given that F = 120 N, and Δp = 240 Kg-m/s
\(F_{ext} = {Δ p \over Δ t}\)
\(120 = {240 \over Δ t}\)
Δt = 2 sec
So the correct answer is option 4.
