Answer:
See Explanation
Explanation:
The question is incomplete, as there are no diagrams or options to provide more information to the question.
The general explanation is as follows:
For the object not to move
(1): The forces acting on the object must opposite each other. i.e. if force A acts at the right (or positive direction), force B will act at the left (or negative direction).
(2) The two forces must be equal.
So, for instance:
If the pair of forces are 5N and 5N in opposite directions, the object wil not move.
However, if one of the forces is greater, the object will move towards the direction of the greater force.
Answer:

Explanation:
Given that
Mass of rifle = M
Initial velocity ,u= 0
Mass of bullet = m
velocity of bullet = v
Lets take final speed of the rifle is V
There is no any external force ,that is why linear momentum of the system will be conserve.
Initial linear momentum = Final linear momentum
M x 0 + m x 0 = M x V + m v
0 = M x V + m v

Negative sign indicates that ,the recoil velocity will be opposite to the direction of bullet velocity.
The work function is what we call the minimum energy that is required by an electron to leave the metal target in the photoelectric effect.
Kinetic energy is the energy of motion.
The formula for kinetic energy is given as
KE = (0.5) m v²
where m = mass of object , v = speed of object.
an object having some speed and mass will have kinetic energy while an object at rest will not have any kinetic energy since the speed of object at rest is zero.
Since at rest speed is zero. an object has kinetic energy only when it is in motion.