Physics On the Road-Lesson 10
- 1. Forces Physics on the Road Lesson 10
- 2. Isaac Newton’s Law We are learning to…. understand that the acceleration of something depends upon it’s mass and the resultant forces acting on it. recall and use the formula Force = mass x acceleration (F=ma) Investigate the effects of an unbalanced force using equations of motion.
- 3. Linking force and motion Philosophers and scientists have been linking force to motion since 300 B.C. Not always well. Forces keep things moving Aristotle 325 BC Forces cause motion but are not needed to keep them moving Galileo 1630 Close but no cigar Newton 1675
- 4. Newton’s Laws First Law If there is no resultant force an object will remain at rest or if moving continue moving at a constant speed. Second Law If there is a resultant force an acceleration proportional to the force will occur. Inertia Reluctance to change speed. Depends upon mass. Force = mass x acceleration (N) (kg) (m/s2) m x a F
- 6. Calculation Questions F U N C A U Q1. What force is needed to give the 800 kg drag car an acceleration of 5 m/s2? Q2. A rocket has a mass of 5000 kg. It’s engines provides a force of 200 000 N. What is the rocket’s acceleration?
- 7. Wacky Race Boeing 747 Mass = 200 000 kg Engine Force = 500 000 N Porsche 911 Mass = 1500 kg Engine Force = 9000 N Honda CBR Mass = 200 kg Engine Force = 1600 N m x a F a = F / m = 500000 / 200000 = 2.5 m/s2 a = F / m = 9000 / 1500 = 6 m/s2 a = F / m = 1600 / 200 = 8 m/s2
- 8. Forces cause acceleration What can we vary? What will that vary? How should we measure this?
- 9. Experiment design Can we measure the acceleration? Are there other measurements we can make to calculate the acceleration? Design your experiment and data table carefully.