1. - Review the relationship of Newton’s 2nd Law (F = m ✕ a) - Introduce the concept of energy - Learn how the energy of an object is stored and transferred TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY

2. > Here is Albert in an elevator. Albert’s mass is 100 Kg. (a) Draw the forces acting on Albert when the elevator is not moving. How big are these forces? Are the forces acting on Albert balanced? What is the net force on Albert? (b) Draw the forces acting on Albert when the elevator is moving upward with a constant speed of 4 m/sec. How big are these forces? Are the forces acting on Albert balanced? What is the net force on Albert? (c) Draw the forces acting on Albert when the elevator is accelerating upward with an acceleration of ½ m/sec 2. How big are these forces? Are the forces acting on Albert balanced? What is the net force on Albert? yes +1000 N –1000 N +1000 N –1000 N +1050 N –1000 N 0 N yes - velocity is constant 0 N no F = m ✕ a = 100 kg ✕ 0.5 m/sec 2 = 50 N

3. Racing balls down tracks Force = mass × acceleration Changing direction of a cart mass did not matter more mass ⇔ more force needed to make same acceleration ↑ ↑ constant AGAIN: Force of gravity on the ball (weight) is proportional to mass EXPERIMENTS WITH THE LAW OF FORCE AND ACCELERATION:

4. Dropping clay Force = mass × acceleration Changing direction of a cart ↑ constant ↑ When distance increases: What forces act on the ball at the moment of impact? EXPERIMENTS WITH THE LAW OF FORCE AND ACCELERATION: 50 cm drop 200 cm drop gravity impact of floor Net upward force → upward acceleration → ball slows to stop

5. - How unbalanced (net) forces produce an acceleration - Understand conceptual problems using Newton’s Laws of Motion - Solve problems involving force, mass and acceleration using Force = mass × acceleration WHAT YOU ARE EXPECTED TO KNOW:

6. NEWTON’S LAWS OF MOTION: Observed in “steering a ball with plastic barriers” lab ; seeing a bubble level stay centered when velocity is constant Observed in comparing straight line plots of force on a cart and acceleration of a rolling ball vs. steepness ; racing steel balls, dropping clay spheres Observed in magnets, balanced forces on scales pulling cart and balancing a mass between 2 scales

7. - Review the relationship of Newton’s 2nd Law (F = m ✕ a) ✓ - Introduce the concept of energy - Learn how the energy of an object is stored and transferred TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY

8. Acceleration of an airborne ball: DISTANCE, VELOCITY AND ACCELERATION vs. TIME: Velocity changes direction Acceleration is always nonzero and downward time distance velocity acceleration Force = weight - this is always constant constant force, constant mass means constant acceleration constant acceleration means velocity changes at constant rate (straight line!) 0

9. EXPERIMENTS WITH THE LAW OF FORCE AND ACCELERATION: Changing direction of a cart Force = mass × acceleration Changing direction of a cart More stretching = more force more mass ⇔ more force needed to make same acceleration ↑ ↑ constant