(FOM) Forces Lesson

Forces

What is a Force?

A force is simply a push or a pull.  A force can cause a change in motion. A force is a vector quantity, meaning that it has both magnitude (size or numerical value) and direction.  Knowing the size of the force and the direction of the force is very important, as it will determine the motion of the object.  Let's use a game of tug of war to explain this concept of forces.  

When each team is pulling with an equal force in opposite directions, then neither team can cause the other team to move. Forces that are equal in size, but in opposite directions are called balanced forces. Balanced forces do not cause a change in motion.  

However, if one team is able to pull with a greater force than the other team, then there will be a change in motion. Forces that cause a change in motion are called unbalanced forces. Unbalanced forces can occur in the same direction or in opposite directions. Unbalanced forces are not equal and opposite.  

More than one force can act on an object at one time. Looking back to the game of tug of war, each team member experiences the applied force of the other people in the game as well as the force of gravity holding them to the ground.  The combination of all of the forces acting on an object is the net force. The net force determines the motion of the object.  For balanced forces, the net force is zero indicating that there is no motion.  

When more than one force is acting on an object, forces that are in the same direction are added together and forces in opposite directions are subtracted.  Suppose you and a friend need to move a piano. To do this, you push on one end and your friend pulls on the other end. Your added forces are enough to move the piano. This is because your forces are in the same direction. Another example is two dogs playing tug of war. Since the dogs are pulling in opposite directions, the forces are subtracted. The net force is the difference between the two forces in the direction of the larger force.

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To review balanced and unbalanced forces, please watch the videos below. You will be shown 5 different scenarios and will determine if the forces acting on the object are balanced or unbalanced.

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