Presentation on theme: "Unit 3 – Newton’s Laws of Motion!"— Presentation transcript:
1Unit 3 – Newton’s Laws of Motion! Hand back testLecture on History of MotionIntroduction to Newton’s 1st & 2nd Law
2Today 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?
13Newton’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.
14Back to Inertia Resistance to change in velocity is caused by mass. Big mass – takes a lot to change its velocity!
15Different inertias The larger mass … Larger resistance to change in velocity
16A 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?
17And 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
19Mass versus volume Mass = amount of matter Volume = how much space the object takes up.
20Mass versus Weight Mass = amount of matter. Weight = force of gravity on an object.
21SI Units Mass = kilogram Weight = Newton So, what is a pound? Mass or weight?
22Calculating weight Weight 1 kg = 9.8 N = mass X acceleration of gravity= mass x (9.8 m/s2)1 kg = 9.8 N
23Check 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?
24Newton’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
25Free 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.
68What forces are acting… On a falling rock?On a book pushed across the floor?On a monkey swinging from a rope?
69F = 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?