Question

when the box is moving ,it experiences a friction force of 20 N to the left , or toward the mover . what force does the mover need to applying order to keep the box moving to the right at 1 m/s?

Answer 1

The mover will need 20 newtons

Answer 2

Force = mass * acceleration
F = ma

Force = 20 Newtons
Mass = ?
Acceleration = 1 m/s

Here, we don't need to find the mass. Which is why this is such a tricky question.

Instead, we need to find the force.

Of course, we know already that force doesn't necessarily require a direction.

F = 20 N

The force needed would be 20 Newtons, as said.