Question #6e96b

1 Answer

Answer:

#v = 8sqrt(5)"m/s"#

Explanation:

Just after bus started
For bus: Displacement, #x = (1/2)# x #(0.2)##t^2#
For man: Displacement, #80 + x = vt#

To get close to the bus:

#0.1 * t^2 = vt - 80# ; eliminating #x# from above two equations

=> #t^2 -10vt +800 = 0#

To get the real solution of the above quadratic equation;

#10v^2 - 4 * 1 * 80 >= 0#

This means that

#v^2 >= 320#

so, the minimum speed will be

#sqrt(v^2) = sqrt(320) => v = 8sqrt(5)"m/s"#