# 11.1 Laws of Motion

```WHO IS THIS HANDSOME FELLA?
(1642-1727)
WHAT CAUSES MOTION?
• EVERT MOTION YOU OBSERVE OR EXPERIENCE IS RELATED TO A FORCE!
• NEWTON DESCRIBED THE RELATIONSHIP BETWEEN FORCE AND MOTION IN 3 LAWS.
FIRST LAW
• AN OBJECT AT REST REMAINS AT REST AND AN IN MOTION MAINTAINS VELOCITY UNLESS IT EXPERIENCES
AN UNBALANCED FORCE.
• “LAW OF INERTIA”
• INERTIA: THE TENDENCY OF AN OBJECT TO RESIST BEING MOVED OR, IF THE OBJECT IS MOVING, TO
RESIST A CHANGE IN SPEED OR DIRECTION UNTIL AN OUTSIDE FORCE ACTS ON THE OBJECT.
• EX: PETE ROSE SLIDE ON ICE VS. PETE ROSE SLIDE ON CONCRETE.
NEWTON’S FIRST LAW
SUMMARY OF FIRST LAW
• MATTER RESISTS ANY CHANGE IN MOTION.
• SMALL FORCE REQUIRED TO MOVE SMALL OBJECT, LARGER FORCE FOR LARGER OBJECT
• SMALL MASS OBJECT IN MOTION WILL HAVE LESS INERTIA THAN LARGE MASS OBJECT IN MOTION.
• COIN, CARD, CUP… EXPLAIN USING WHAT YOU KNOW ABOUT NEWTON’S FIRST LAW OF MOTION.
NEWTON’S SECOND LAW
• THE UNBALANCED FORCE ACTING ON AN OBJECT EQUALS THE OBJECT’S MASS TIMES ITS ACCELERATION.
• FORCE=MASS X ACCELERATION
• EXAMPLE: CONSIDER PUSHING AN EMPTY SHOPPING CART OR ONE FILLED WITH GROCERIES.
• ONE PERSON PUSHING A CAR COMPARED TO 5 PEOPLE.
PRACTICE
• ZOOKEEPERS LIFT A STRETCHER THAT HOLDS A SEDATED LION. THE TOTAL MASS OF THE LION AND
STRETCHER IS 175 KG, AND THE UPWARD ACCELERATION OF THE LION AND STRETCHER IS 0.657 M/S2.
WHAT IS THE UNBALANCED FORCE NECESSARY TO PRODUCE THIS ACCELERATION OF THE LION AND THE
STRETCHER?
• M= 175KG, A=0.657 M/S/S
• F=M X A
• F= 175 KG X 0.657 M/S/S
• F=115N
FORCE CAN GO ON TOP ONLY! (SIMPLY
DIVIDE BOTH SIDES BY WHAT IS DESIRED)
• A BASEBALL ACCELERATES DOWNWARD AT 9.8 M/S/S. IF THE GRAVITATIONAL FORCE IS THE ONLY FORCE
ACTING ON THE BASEBALL AND IS 1.4 N, WHAT IS THE BASEBALL’S MASS.
• M=F/A
• A SAILBOAT AND ITS CREW HAVE A COMBINED MASS OF 655 KG. IGNORING FRICTIONAL FORCES, IF THE
SAILBOAT EXPERIENCES A NET FORCE OF 895 N PUSHING IT FORWARD, WHAT IS THE SAILBOAT’S
ACCELERATION?
• A=F/M
PG. 351 4,5,6
```