How many laws did Newton create? Agenda Turn in SQ3R Newton’s Laws lab

What is force? Agenda for Wednesday Oct 27th Newton’s Laws Notes

Forces Def – an action exerted on an object to change the object’s state of motion (resting or moving) Magnitude and direction Units: Newtons (N) Net force – total force on an object When there is a net force on an object, the object accelerates in the direction of the net force If net force = 0, then the object does not move

Balanced forces Net force = 0, no movement Forces are balanced An object standing still will not move An object moving will not stop

Unbalanced Forces Net force is greater than zero, unbalanced force Object will move

Friction Force that opposes motion between two surfaces that are in contact 2 types Static – friction between two forces at rest, initial friction an object must overcome Kinetic – friction between two moving objects Static friction is usually greater

Newton’s Laws He was born the same year that Galileo died Newton had ideas about motion, which he called his three laws of motion Also had ideas about gravity, the diffraction of light, and forces Physics and Math Helped create Calculus

What is the net force on the object below? Agenda for Thursday Oct 28th Finish Newton’s Laws Force problems Questions on page 336

First Law Law of inertia An object at rest will stay at rest and an object in motion stays in motion unless acted on by an external force Inertia – tendency of an object to stay at rest or stay in motion Mass is a measure of inertia Small mass = less inertia Seatbelts

Second Law The unbalanced force acting on an object equals the object’s mass times its acceleration F=ma Force is measured in Newtons (N) 1 N = 1 kg x 1 m/s2 Q: What is the force necessary for a 1600 kg car to accelerate forward at 2.0 m/s2 ?

2nd Law Problem Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.05 m/s2 . Using Newton's Second Law, compute how much force Mike is applying to the car.

Third Law For every action there is an equal and opposite reaction Opposite in direction. Whenever an object pushes another object it gets pushed back in the opposite direction equally hard Example: Balloon full of air being released

What are Newton’s 3 Laws? Agenda for Friday Oct. 29th Quiz Go over Force Problems Video

A person that weighs 50 kg runs and hits a wall with a force of 50 N A person that weighs 50 kg runs and hits a wall with a force of 50 N. What was the person’s acceleration as they hit the wall? With what force did the wall hit the person? Agenda For Monday Nov. 1st Review Newton’s Laws Lab Questions on page 336

Why does a semi-truck take longer to stop than a small car? Agenda Tuesday Nov 2nd Momentum Gravity

Momentum Def. – mass and velocity of an object P=mv Units: kg x m/s AND direction Objects with larger mass have more momentum Objects moving faster have more momentum

Calculate Momentum Calculate the momentum of a 6.00 kg bowling ball moving at 10 m/s toward the pins. Calculate the momentum of the following objects: a. a 75 kg speed skater moving forward at 16 m/s b. a 135 kg ostrich running north at 16.2 m/s c. a 5.0 kg baby on a train moving east at72 m/s d. a seated 48.5 kg passenger on a train that is stopped

Force and Momentum To catch a ball you use a force to stop the ball You change the ball’s momentum If you increase the time to catch the ball you reduce the force

Momentum and Collisions The total amount of momentum is an isolated system in conserved m1v1 = m2v2 During a collision, momentum can be transferred Hitting billiard ball

Cart collisions

Gravity Read pages 352 – 359 Answer questions 1-6 on page 359

How does weight differ from mass? Agenda for Wednesday Nov 3rd Gravity Energy

Force of Gravity All objects in the universe attract each other through gravitational force Mass increases – force of gravity increases Distance increases – force of gravity decreases

Force of Gravity Free fall – only force of gravity is affecting an object Calculate the acceleration at which an object free falls Earth – 9.8 m/s2

Force of Gravity Weight is not the same as mass Depends on gravity Different locations have different gravities and therefore different weights Force of gravity on an object is weight weight = mass x free fall acceleration w=mg Newtons (N)

Projectile Motion Vertical and horizontal components No affect on each other Combined they form a curved path Same acceleration downward because of gravity and will land at the same time