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
.
