N EWTON ’ S 1 ST L AW OF M OTION The Law of Inertia
S PEED : DISTANCE COVERED PER UNIT OF TIME or Speed = distance/ time
V ELOCITY P RACTICE P ROBLEMS 1. What is the speed of a rocket that travels 9000 meters in seconds? 2. The space shuttle travels 700 m/s. How long will it take it to go 500 kilometers? 3. A plane that travels 180,000 meters in one hour has a speed of _____ m/s. 4. A plane flies 80 km in 10 minutes and then flies 100 km in 20 minutes. What is the average speed of the plane?
V ELOCITY K EY m/s s m/s km/hr or 100 m/s
V ELOCITY : A VECTOR QUANTITY
M OTION IS RELATIVE Everything is always moving. Even when you are “standing still” you are speeding through space. What is your speed relative to Earth? What is your speed relative to the Sun? 0m/s 30km/s
G RAPHING M OTION Distance vs. Time Graphs
G RAPHING V ELOCITY Increasing Speed
G RAPHING V ELOCITY At Rest
G RAPHING V ELOCITY At Rest
INERTIA The tendency of an object to resist a change in its motion.
An object in a state of uniform motion tends to remain in that state of motion unless an external net force is applied to it uniform motion net force uniform motion net force acceleration Motion that is not changing/ constant An unbalanced force that results in acceleration The rate at which an object’s velocity changes acceleration
I S R EST U NIFORM M OTION ? YES…it is a constant velocity of ZERO m/s!
I F AN OBJECT IS ACCELERATING CAN IT HAVE CONSTANT MOTION ? No…by definition acceleration is a CHANGE in velocity!
S PORT S CIENCE F ORCE VIDEO eature=results_video&playnext=1&list=PLB8BB91 68E6F5F978
T HE GREATER THE VELOCITY THE GREATER THE Inertia RESISTANCE TO A CHANGE IN MOTION Think about trying to stop a bullet with your hand.
T HE GREATER THE MASS THE GREATER THE Think about trying to push a plane down the runway. Inertia RESISTANCE TO A CHANGE IN MOTION
C HECK YOUR UNDERSTANDING POD #1: Why will the coin drop into the glass when a force accelerates the card? POD #2: Why does the downward motion and sudden stop of the hammer tighten the hammerhead? POD #3: Why is it that a slow continuous increase in the downward force breaks the string above the massive ball, but a sudden increase breaks the lower string?
NET FORCE The Combination of All Forces that act on an object Applied ForcesNet Force
A STRONOMY A PPLICATION The earth moves around the sun.