Presentation Transcript
Motion and Forces :Motion and Forces Physical Science 2.3
Forces :Forces Force- push or pull that one object exerts on another
Examples: hitting a baseball, throwing a basketball, etc.
Forces aren’t always noticeable
Floor pushes up on you- otherwise you’d fall
Forces influence motion
Changes the velocity- either the speed or direction
Forces :Forces Net Force- Total force on an object
If forces are balanced, no movement occurs- net force is zero
Balanced forces- forces equal in size but opposite in direction
Why don’t you fall through the floor?? http://www.teachersdomain.org/resources/phy03/sci/phys/mfw/goalstring/index.html
Unbalanced force- force that is not balanced by another force
Results in movement
Forces :Forces Strong force to the right, weak force to the left = move to the right
Inertia- the tendency of an object to resist any change in motion
If moving- stays moving unless acted on by unbalanced force
If stopped- stays stopped unless acted on by unbalanced force
Car should stay in motion once it starts in motion
Problem: friction opposes motion
Forces :Forces Inertia and injury
In car crashes, you tend to remain in motion until you are acted on by a force (until you hit something that resists you)
Seatbelts
Prevents people from being thrown from the car- provides unbalanced force to stop inertia
Increases time over which patient slows