130 likes | 225 Views
Newton’s Second Law. http://www.youtube.com/watch?v= UyI3IL46yq4. Do-Now. Write down what you remember from the lab on Friday. What is the relationship between force and acceleration? What is the relationship between mass and acceleration?. Force and Newton’s Second Law. What is force?
E N D
Newton’s Second Law http://www.youtube.com/watch?v=UyI3IL46yq4
Do-Now • Write down what you remember from the lab on Friday. • What is the relationship between force and acceleration? What is the relationship between mass and acceleration?
Force and Newton’s Second Law • What is force? • Any push or pull • When the force increases and the mass stays constant, the acceleration increases • When the mass increases and the force stays constant, the acceleration decreases
Newton’s Second Law • Fnet = ma • Fnet = force (in Newtons) • m = mass (in kg) • a = acceleration (in m/s2)
Weight • the effect of the acceleration due to gravity • Always directed downward • Dependent on location • Weigh more or less on the moon? Why?
Mass • Amount of matter in an object • Constant for a particular object • Independent of location • Do you have a different mass on the moon?
Weight Equation • Fg = mg • Fg = force due to gravity (in Newtons) • m = mass (in kg) • g = acceleration due to gravity (10 m/s2)
Weight in an Elevator • http://www.youtube.com/watch?v=2k-2IlJcaHg
Net Force and Acceleration • Net force: the result of all forces exerted on an object • If forces are exerted in the same direction, they are added • If forces are exerted in opposite directions, they are subtracted • Acceleration is always in the direction of the net force (largest force) • If the Net force is zero, the object is not accelerating • Can it be moving though?
Free Body Diagrams • Drawing to help understand forces • Draw arrows away from the object to represent forces
Equilibrium • When the acceleration of the object is zero • Net force is also zero • Two types • Static: Object is not moving • Dynamic: Object is moving at constant velocity
Static Objects • If the net force is zero AND the object is not moving, it is said to be static • Weight pulls objects down • Normal force • Supports them from falling • Acts perpendicular to a surface
And now your favorite professor… • http://www.youtube.com/watch?v=_XJrY2sKfFQ