If a force F is applied on a body and it moves with a velocity V, the power will be
The driver of a train moving with a constant velocity v1 along a straing track sights another train at a distance d ahrad of him on the same track moving in a same direction with a constant speed V2. He at once applies a brakes and gives his train a constant retardation f. There will be a collosioc of yhe trains if......?
a) v1 > V2 amd (V1 -V2)2 /2f < d
b) V1<V2 and (V1+V2)2 /2f > d
c) V1 > V2 and ( V1-V2)2 /2f > d
d) V1>V2 and (V12 - V22)/2f > d
Force of viscosity acting on a spherical body of radius r moving with velocity v through a fluid of viscosity η is given by