physics set 4

Q.1 An object having spherical shape of radius ‘r’ experiences a retarding force F from a fluid of coefficient of viscosity ‘η’ when moving through the fluid with speed ‘v’. What is the ratio of retarding force to speed?
A) 6πη r2                              C) 6πη r
B) 6πη/r2                             D) 6πη/r
Q.2 When the drag force is equal to the weight of the droplet, the droplet will fall with:
A) High Speed               C) Certain acceleration
B) Low Speed                D) Constant Speed
Q.3 The density of blood is:
A) Less than water                    C) Greater than water
B) Nearly equal to water            D) Three times that of water

Q.4 Stokes’ Law for steady motion in a fluid of infinite extent is given by
A) F = 6πηrv                             C) F = 6πηr²ρ
B) F = (4/3)πr³ρg                       D) F = 2gr²ρ/9η
Q.5 If speed of efflux through a small hole in a large tank is 9.8 m/s. Find the height at the fluid above the hole
A) 1 m                          C) 4.9 m
B) 9.8 m                       D) 19.6 m

Q.6 Flow speed of the fluid through a non­uniform pipe increases from 1 m/sec to 3 m/sec. If change in P.E. is zero, then pressure difference between two points will be: (density of the fluid = 1000 kg/m3)
A) 1000 N/m²                                      C) 8000 N/m²
B) 9000 N/m²                                      D) 4000 N/m²