When an object is moving at a constant velocity, the net force acting on it must be zero. This is because the net force is responsible for any changes in the object's motion (acceleration), and if the object is moving at a constant velocity, there is no acceleration, meaning the net force is zero.
To calculate the net force from two forces acting on an object, you need to consider their magnitudes and directions. If the two forces are along the same line, you can simply add or subtract their magnitudes, depending on their directions.
If the forces are in the same direction, you add their magnitudes:
Net Force = Force 1 + Force 2
If the forces are in opposite directions, you subtract their magnitudes:
Net Force = Force 1 - Force 2
Remember to consider the appropriate signs (+/-) to indicate the direction of the net force.
However, if the forces are not along the same line, you need to use vector addition to determine the net force. In that case, you would need to break down the forces into their horizontal and vertical components, add or subtract the respective components separately, and then combine them to find the resultant net force.
It's important to note that when an object is moving at a constant velocity, the net force is zero, which means the sum of all forces acting on the object is balanced.