POSITION AND MOTION
A person might describe the position of the bike by saying that it is in between the two doors. Also, the back tire is leaning against the small tree. It is also below the power line.
motion – a change of position of an object
The motion of these bikes can be seen in this picture since it is blurry. Being in motion means that the bike is constantly changing its position.
FRAME OF REFERENCE
A frame of reference uses another object and position to describe the motion.
In the picture above, the first picture shows that the car is to the right of the tree. The TREE is the frame of reference. The second picture shows that there was motion because we can see that the car is now to the left of the tree. The frame of reference allows us to see that the car moved.
SPEED and VELOCITY
speed – the measure of an object’s change in position during a unit of time
speed = distance divided by time
velocity – the speed and direction of an object
Just add the SPEED and a DIRECTION! For example, 50 miles per hour, north.
force – a push or pull of any kind
Forces are measured in NEWTONS: For example, 50 N of force was applied to the chair.
acceleration – any change in speed OR direction of an object
inertia – the property of matter that keeps an object at REST or keeps it moving in a STRAIGHT LINE
WEIGHT vs. MASS
Picture A (ice) has less friction. There is less resistance so the boy will move faster.
Picture B (grass) has more friction. There is more resistance and force stopping the boy so he will not go down the hill as fast.