Force and Friction

What is Force? A force is a push or pull that acts on an object A force can cause a resting object to move, or it can accelerate a moving object by changing the object’s speed or direction

Measuring Force: We measure force by using a unit called Newtons (N) Measuring Force: We measure force by using a unit called Newtons (N). One Newton is the the force that causes a 1 kilogram mass to accelerate at a rate of 1 meter per second

Representing Force: You can use an arrow to represent the direction and strength of a force. The direction of the arrow represents the direction of the force, the length of the arrow represents the strength or magnitude of the force.

Example: There is a force acting towards the left and a force acting towards the right The force acting towards the right is larger because the arrow is longer

Combining Force: Net Force You can combine forces and subtract forces. We call this the net force You can combine force arrows to show the result of how forces in the same direction add together You can also show how forces in opposite directions subtract from one another

Example 1: Combining Forces There are two forces acting on this object Force 1 (F1) = 6 Newtons East Force 2 (F2) = 3 Newtons East

To combine these two forces, simply add F1 and F2 to find a “net force’ (R) F1 = 6N F2 = 3N R = 6N + 3N R = 9N

Example 2: Subtracting Forces If two forces are acting opposite of one another, to find an object’s net force, we must subtract forces. 4 N 9 N

To find the net force, we can subtract one force from another F1 = 4N F2 = 9N For this example, we will subtract F1 from F2 R = F2-F1 R = 9N – 4N R = 5N

Example 3: Multiple Forces Sometimes more than 2 forces act upon an object

In this case, we would add together the forces going right first F1 = 16N F2 = 8N F1 + F2 = 24N We would then subtract all of the forces going left R = 24N – 14N R = 10N The net force is 10 Newtons

Balanced Forces When 2 or more forces are acting in the opposite direction, but are applying the same amount of force on an object, we say that the forces are balanced

Balanced forces will always equal 0 Newtons 10 N – 10N = 0 N