Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep...
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Transcript of Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep...
![Page 1: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/1.jpg)
Force
Chapter 5
![Page 2: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/2.jpg)
Aristotle and Galileo
Aristotle
-all objects require a continual force to keep moving (a rolling ball slows down over time)
Galileo
-Realizes the existence of friction
-In space (no friction) a moving object continues forever.
![Page 3: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/3.jpg)
Isaac Newton (1642 to 1727)
• born the year Galileo died, 1642.
• Invented calculus (while living in seclusion to avoid the plague)
• Three laws of motion• Principia
Mathematica
http://en.wikipedia.org/wiki/Image:GodfreyKneller-IsaacNewton-1689.jpg
![Page 4: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/4.jpg)
Newton’s Three Law’s of Motion
1. All objects remain at rest or in uniform, straight-line motion unless acted upon by an outside force. (inertia)
2. Force = mass X acceleration
3. Every action (force) has an equal and opposite reaction (force).
![Page 5: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/5.jpg)
The First Law
• All objects remain at rest or in uniform, straight-line motion unless acted upon by an outside force. (inertia) – Inertia –tendency of an object to remain at rest or in
constant motion.– mass - measure of inertia.– Mass and inertia are directly proportional
![Page 6: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/6.jpg)
The First Law
Ball in jar example:
![Page 7: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/7.jpg)
Does it take less force to push the elephant (ignore friction) on earth or on the moon?
![Page 8: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/8.jpg)
Does it take less force to move the elephant if he is “weightless” in space?
![Page 9: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/9.jpg)
Inertial Reference Frames
• Non-accelerating (constant velocity) reference frame
• All laws of physics are identical in all Inertial Reference Frames
• Cannot tell if you are moving in an Inertial Reference Frame
![Page 10: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/10.jpg)
Free Body Diagrams
• Only show forces NOT resolved components
Draw a free body diagram for a box sitting on a table.
Draw a free body diagram for a box sitting on a ramp
Draw a free body diagram for a box being pushed up a ramp
![Page 11: Force Chapter 5. Aristotle and Galileo Aristotle -all objects require a continual force to keep moving (a rolling ball slows down over time) Galileo -Realizes.](https://reader031.fdocuments.us/reader031/viewer/2022020111/56649eec5503460f94bfe326/html5/thumbnails/11.jpg)
A hockey puck slides at constant velocity across the ice. Which of the following is the correct free-body diagram?
Free Body Diagrams: Ex. 2