| A | B |
|---|
| Speed | a measure of how far something travels in a certain time |
| Kilometers per hour | the number of kilometers something can travel in 1 hour |
| Velocity | a measure of speed in a certain direction |
| Inertia | tendency of a moving object to stay in motion or to stay still |
| people jerk backward | if a bus moves forward suddenly ..... |
| people jerk forward | if a bus stops suddenly...... |
| you can stop peddling & the bike will keep moving; inertia keeps the bike moving! | After you pedal your bike for awhile..... |
| Valentines Day! | February Holiday....... |
| Pairs of Forces | one force pushes in one direction, while another pushes with equal strength in the opposite direction ex. frog |
| gravity | a force that acts to pull pairs of objects together |
| mass | amount of matter in an object |
| attract each other | objects with the SAME or nearly the same mass |
| also attract each other equally but the object with less mass moves more b/c less force is needed | objects with DIFFERENT masses |
| weight | the force gravity exerts on an object's mass |
| person's mass stays the same but weight is 1/6 less | person on the moon |
| have a GREATER attraction | objects closer to each other |
| have a WEAKER attraction | objects far apart from each other |
| acceleration | rate of change in speed or direction of movement |
| gravity makes objects FALL FASTER | as the distance between the object & ground decreases |
| gravity causes their ACCELERATION to be the same | if a soccer ball & bowling ball are dropped at the same time_____________ so they drop at the SAME time |
| friction | force that resists the movement of one surface past another surface |
| sand, rough, bumpy surface, carpet | sources of friction |
| putting wheel on objects & oil or grease (slippery material) | reduces friction |
| air resistance | friction caused by gas molecules in the air hitting an object & slowing down |
| tucking your head down & keeping arms close to the body | when riding a bike, reduce air resistance by....... |
| streamline ex. founded nose of an airplane | to design, smooth, rounded surfaces on an object so it slips thru the air with the least possible resistance; |
