Forces and Motions
Force
it has both size and direction
Measuring force
one newton is the force needed to change the speed of a one-kilo object
force is measured in units called newtons
Friction
is the force that resists the movement of an object
it is a puh or pull
Gravity
it is the force of attraction between any object in the universe
it affects how plants and our bones develop
Newton was the first to explain gravity
Motion
Speed is a measure of how fast an object is moving
velocity is the speed of an object in particualr direction
acceleration is the rate at which velocity changes
Newton's laws of motion
First law
Newton's first law states that, if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. This is known as the law of inertia.
Second law
The acceleration of an object depends on a mass of the object nd the sizeof the net force applied
Third law
If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A. This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself.