Net force is calculated using newtons. To calculate net force you have to add the two measures together if the arrow is pointing in the same direction meaning it's an unbalanced force. If the arrows are pointing in different directions you subtract the measures and the side with the greater amount of force will make the object move in that direction. After you subtract the two measures whatever your result came out to be that is your net force on that object. Net force will never equal zero.

How is Net Force Calculated?

Net force can't be calculated here because this is a balanced force. It has the same amount of force pushing in different directions so there is no need to subtract because it's zero.

Examples:
*Sliding a box across the floor
*playing tug of war with your class