forces: newton’s second law of motion - miami arts charter
TRANSCRIPT
Intro to Forces
○ Forces: ○ a push or pull that involves the interaction
between two or more objects ○ Vectors (they have magnitude and
direction) ○ There are 5 fundamental forces (gravity,
normal, air resistance, friction, applied) ○ can be represented by Free Body
Diagrams
Intro to Newton’s Second Law
○ How do the cheerleaders on the bottom get the cheerleader to fly through the air?
○ What would happen if they didn’t apply enough force?○ What would happen if they applied too much force? ○ Why do cheerleaders choose a lightweight person as a “flyer”? ○ Would the necessary force change if the “flyer” weighed more?
Isaac Newton’s Laws of Motion
○ Newton’s Second Law: Newton was able to not only describe the relationship between force, mass and acceleration; he discovered a simple formula that described the relationship numerically.
For example: An object falling with an acceleration of 10 m/s2 with a mass of 10 kg is falling with a force of _____ Newtons
○ F= m x a
○ F =○ F =
10 kg 10 m/s2x
100 Newtons
Isaac Newton’s second law of motion: The Net Force acting on an
object are equal to the mass of the object times its acceleration.
FORCE IS A VECTOR!
Force is proportional to the mass and the acceleration. For example, if the acceleration increases, so will the Force.
Newtons (N) kg m/s2
Newton’s Second Law of Motion
Variable UnitForce Newtons (N) Mass Kilograms (kg), Grams
(g) Acceleration m/s2
FAMx÷÷
Practice!
Force Mass Acceleration10 N 2 kg 20 N 2 kg 20 N 4 kg 2 kg 5 m/s2
10 N 10 m/s2
5 m/s2
10 m/s2
5 m/s2
10 N1 kg
YOUTUBE VIDEO
https://www.youtube.com/watch?v=ZvPrn3aBQG8
BELLRINGER: newton’s second law Roberto and Laura are studying across from each other at a wide table. Laura slides a 2.2 kg book toward Roberto. If the net force acting on the book is 1.6 N to the right, what is the book’s acceleration?
The net force of a golf cart is 390N north. If the cart has a total mass of 270 kg, what are the magnitude and the direction of the cart’s acceleration?
NET FORCES
Net Forces are the total amount of force acting on a object.
To find the Net Force, you add or subtract the total amount of Forces. Remember: Forces are vectors, so they can be negative!
NET FORCES
Free Body Diagrams help us determine the presence of forces.
Forces can be balanced or unbalanced- Balanced Forces= Net Forces are equal to 0 and the
acceleration is 0- Unbalanced Forces= Net Forces are not equal to 0
EXAMPLE 3: What is the net Force of needed to accelerate a grocery sack (weighing 210 N) upward at 1.5 m/s2?