Presentation on theme: "Unit 3 – Newton’s Laws of Motion!"— Presentation transcript:
1 Unit 3 – Newton’s Laws of Motion! Hand back testLecture on History of MotionIntroduction to Newton’s 1st & 2nd Law
2 Today you should learn… What is mass?What is inertia?What did Aristotle think the natural state of objects was?What is Newton’s 1st Law?If you were in outer space and you threw a ball 10 m/s when would it stop?
13 Newton’s First Law – Law of Inertia Objects that are at rest stay at rest until a force acts on it.An object in motion will stay in motion, until a force acts on it.
14 Back to Inertia Resistance to change in velocity is caused by mass. Big mass – takes a lot to change its velocity!
15 Different inertias The larger mass … Larger resistance to change in velocity
16 A ball is rolling on a counter… And slowly comes to a stop.What would Aristotle have said was the cause?What would Galileo and Newton have said?And you? What do you say?
17 And force is … A push Or a pull In the SI unit of measurements A Newton (N)
18 “Net” Force Takes into account ALL the forces acting on an object! If you have a 6 N force pushing and a 4 N force pullingThe net force is a 2 N force pushing
19 Mass versus volume Mass = amount of matter Volume = how much space the object takes up.
20 Mass versus Weight Mass = amount of matter. Weight = force of gravity on an object.
21 SI Units Mass = kilogram Weight = Newton So, what is a pound? Mass or weight?
22 Calculating weight Weight 1 kg = 9.8 N = mass X acceleration of gravity= mass x (9.8 m/s2)1 kg = 9.8 N
23 Check your understanding… What is mass?What is inertia?What did Aristotle think the natural state of objects was?What is Newton’s 1st Law?If you were in outer space and you threw a ball 10 m/s when would it stop?
24 Newton’s Second Law:A net force acting on an object will cause the object to accelerate in the direction of the net force.Force = mass X acceleration
25 Free Body Diagrams:The size of the arrow in a free-body diagram reflects the size of the force.The direction of the arrow shows the direction the force is acting.
68 What forces are acting… On a falling rock?On a book pushed across the floor?On a monkey swinging from a rope?
69 F = ma If you double the mass… If you double the force… What happens to the acceleration?If you double the force…What is your acceleration…If you move with a constant velocity?What is the net force if that is true?