Suppose there is a body lying on a rough surface i.e friction is there. Initially the body is at rest.
Let the frictional force be $f$
And the applied force be $F$
So it is said that if we apply a force and this applied force becomes equal to the frictional force then the body will move with constant velocity.
How is this possible because when the applied force becomes equal to the frictional force then the net force acting on the body is zero i.e.
$$F=f$$
$$F-f=0$$
The net force acting on it is zero so according to Newton's first law of motion it should remain at rest
because the net acceleration is zero and initially it is at rest so its final velocity after any amount of time should be zero.
But in the books it is written that it will move with constant velocity. How is this possible.
And if it moves with constant velocity then with how much?
I am totally confused here.
Best Answer
0 is also a constant velocity.
You are completely correct in your analysis here. And they are also correct in their statement, although it is very general. If all forces balance out, then there is no acceleration, meaning no change in velocity.
If the velocity was 0, then it stays zero. Of it was, say, 10 m/s, then it stays 10 m/s. The velocity remains unchanged. It is constant regardless of its value including 0.