Question

Try this u must enjoy it: Suppose Superman can run with a speed of infinite m/s.If he starts to run then how much TIME he will take to cover 200m distance on a ground with coefficient of friction 0.1?If Superman , Batman, Shaktimaan, Bal Veer can run with speeds infinity, 10^ 8,10^10,10^12 m/s respectively.If they starts simultaneously Then which Superhero will win 20 Km marathon on the same ground??(do not care if there is a speed limit in universe....)( solved in comment... :))

Answer 1

As Superman starts from rest :
initial velocity of him (u) = 0;
this is the FRICTION which provide our superhero an acceleration.
friction force = 0.1×M×g
(where M is the mass of Superman and g is acceleration due to gravity )
Max Acceleration provided by ground =
(0.1×M×g)/M = 0.1g m/s².
Hence time taken(t) to cover 200m is given by using [ s= ut +½at²];
200= ½(0.1g)×t²;
=> t= 20 seconds (LOL!)
Now the second situation which superhero will win the race :
as this is only the friction that provide acceleration to all our superheroes starting from rest and for all equal to 0.1g.
Hence all our superheroes finish the race at same time !!!!!!