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Today’s special. Hw check – vocab Test results Notes HW for next time : HW I due. Newton’s Third Law of Motion. PAe.7: Explain the motion of objects on the basis of Newton’s three laws of motion: inertia; the relationship among force, mass, and acceleration; and action and reaction forces.
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Today’s special • Hw check – vocab • Test results • Notes • HW for next time: • HW I due
Newton’s Third Law of Motion PAe.7: Explain the motion of objects on the basis of Newton’s three laws of motion: inertia; the relationship among force, mass, and acceleration; and action and reaction forces. PAa.1: Generate hypotheses on the basis of credible, accurate, and relevant sources of scientific information. PAa.2: Use appropriate laboratory apparatuses, technology, and techniques safely and accurately when conducting a scientific investigation. PAa.9: Use appropriate safety procedures when conducting investigations.
Question • When a rocket blasts off, if it was not near the ground, would it take off?
Newton’s Third Law • Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first
Simple rule • Action: Object A exerts force on object B • Reaction: Object B exerts a force on object A
Action and reaction • Effects on objects differ if their masses are different • a = F/m • Decreasing mass makes the acceleration greater
Action and reaction forces act on different objects • Forces cancel only when they act on the same body
Donkey cart • Equal and opposite? • Donkey pulls and cart and pushes on road
Bull fights • Why are they dangerous?
Tug-of-war • How does it work?
Question • When a rocket blasts off, if it was not near the ground, would it take off?
Homework • Chapter Review HW: pp. 80-82 • I. Review questions2-20 even (due date: ____________) • II. Exercises 2-20 even; Problems 1-8 (due date: __________)
Today’s special • HW check; Q & A • Lab • Newton’s Laws video • Lab due next time! Don’t forget to write your conclusion
Today’s special • Turn in lab on front table • Some equations for HW II • Work on HW II with table partner (work on problems, first!) • Handout: Newton’s 3rd Law • New seating chart
Some equations for HW II • F=ma • a=v/t • F1=-F2
Example • Billy rides his bike from rest to 8 m/s in 4 s. How much force did Billy apply to his bike if he and his bike have a mass of 75 kg?
Example • Sally pushes her skateboard with a force of 5 N. The skateboard has a mass of 2 kg. How fast is it going after 3 seconds?
Today’s special • Student Agenda grade (planner) • HW II check • Computer project • Practice Test on Smartresponse system; enter answers, make corrections before turning in next class • Test 4 next time!
Today’s special • Turn in Practice test on front table • Test 4 Newton’s 3rd Law, enter MC answer on smart response • Turn in test completed with sentences & essays • Get Vocab 5: Momentum; work quietly until everyone has finished their test. • Movie time!