A) 1 s
B) 2 s
C) 3 s
D) 4 s
Correct Answer: D
Solution :
\[S=ut+\frac{1}{2}g{{t}^{2}}\] or \[40=-10\,t+\frac{10}{2}\,{{t}^{2}}\] or \[{{t}^{2}}-2\,t-8=0\] or \[(t+2)\,\,(t-4)=0\] \[\Rightarrow \] t = 4 s as t cant be negative.You need to login to perform this action.
You will be redirected in
3 sec