1 ) Can an instantaneous velocity of an object be equal to the average velocity of an object ?
When the acceleration is zero or velocity is constant . So distance - time graph will be straight .
2 ) When a bullet is fired by a gun , the gun recoil backward with a velocity . . . . . . . . . . that of bullet .
A ) greater than , B ) lesser than ,
C ) equal to , D ) None of these ,
Correct Answer : - C ) equal to ,
3 ) The fog droplet falls vertically through air with acceleration equal to . . . . . . . . . . . : -
A ) finite , B ) infinite ,
C ) zero , D ) None of these ,
Correct Answer : - C ) zero ,
Because fog droplet when falling vertically in air experience " air drag forces "
Air drag force = gravitational force " g " .
Fnet = 0 ,
So ma = 0 ,
So a = 0 . And it means acceleration will be zero .
4 ) Static equilibrium : - When body is at rest .
Dynamic equilibrium : - When body is moving with uniform velocity .
5 ) The drift velocity of free electrons is of order of 10 ^ ( -5 ) m / s .
6 ) The ratio of numerical values of average velocity and average speed of a body is always . . . . . . . . . . . ,
A ) finite , B ) infinite ,
C ) unity or less , D ) None of these ,
Correct Answer : - C ) unity or less ,
7 ) At the top of trajectory of a projectile , the direction of its velocity and acceleration are . . . . . . . . . . . to each other .
A ) perpendicular , B ) parallel ,
C ) None of these ,
Correct Answer : - A ) perpendicular ,
8 ) A boat of mass 4o kg is at rest . A dog of mass 4 kg moves in the boat with a velocity of 10 m / s . What is velocity of boat ?
A ) 1 m / s , B ) 2 m / s ,
C ) 3.12 m / s , D ) None of these ,
Correct Answer : - A ) 1 m / s ,
Solution : -
m1 v1 = m2 v2 ,
40 x v1 = 4 x 10 ,
v1 = 1 m / s , Answer .
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