A) 5 s
B) 20 s
C) 40 s
D) 80 s
Correct Answer: C
Solution :
From Newton?s second law of motion. Force = mass\[\times \] acceleration \[{{a}_{y}}=-\frac{5}{5}\,m{{s}^{-2}}\,=-1\,m{{s}^{-2}}\] From equation of motion \[{{v}_{y}}={{u}_{y}}+{{a}_{y}}t\] Where \[{{v}_{y}}\] is initial velocity along y-axis, t is the time and \[{{v}_{y}}\] is the final velocity along y-axis. Given \[{{v}_{y}}=0,\,\,{{u}_{y}}=40\,\,m{{s}^{-1}},\,\,{{a}_{y}}=-1\,\,m{{s}^{-1}}\] \[\therefore \,\,\,\,\,\,\,\,0=40-1\times t\]\[\Rightarrow \,\,t=40\,s\]You need to login to perform this action.
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