A 10 kg box is pulled across the floor at a constant velocity of 3.0m/s. If the box is pulled with a force of 40 N, what's the size of the frictional force between the box and the floor?
At constant velocity, the pulling force equals the friction force (for a level surface)
To find the size of the frictional force between the box and the floor, we can use Newton's second law of motion. According to Newton's second law, the net force acting on an object is equal to the product of its mass and acceleration.
In this case, since the box is moving at a constant velocity, its acceleration is zero. Therefore, the net force acting on the box must also be zero.
The net force acting on the box can be calculated by subtracting the pulling force from the frictional force. If the box is moving with constant velocity, the frictional force between the box and the floor must be equal in magnitude and opposite in direction to the pulling force.
Given that the pulling force is 40 N, we can conclude that the magnitude of the frictional force between the box and the floor is also 40 N.