Presentation on theme: "- Newton’s First and Second Laws - Gravity 3 - Newton’s Third Law"— Presentation transcript:
1- Newton’s First and Second Laws - Gravity 3 - Newton’s Third Law Chapter 12 - Forces- Newton’s First and Second Laws- Gravity3 - Newton’s Third Law
2TN StandardsCLE : Investigate and apply Newton’s three laws of motionCLE : Explore the difference between mass and weightCLE : Relate gravitational force to massCLE : Examine the Law of Conservation of Momentum in real-world situationsCLE.3202.Math.1: Understand the mathematical principles behind the science of Physics
3BellworkHow many laws of motion did Newton create?
41 – Newton’s 1st and 2nd Laws Key Questions:What makes an object speed up, slow down, or change directions?What determines how much an object speeds up or slows down?
5Newton’s First LawAn object at rest remains at rest and an object in motion maintains its velocity unless it experiences a net forceObjects change their state of motion only when a net force is appliedObjects tend to maintain their state of motion
6Inertia “Laziness” of all matter based on mass Is the tendency of an object to stay at rest or to move at constant velocity ( if moving )Seat belts and car seats
7QuickLab – Newton’s 1st Law Place an Index Card over a glass; Coin on cardFlick the card sideways off the glass – what happens to the coin?Does coin move with Index Card?Repeat but slowly pull card sideways – what happens to the coin?Explain the results using Newton’s 1st LawIn your notebook ( lab grade )
8Newton’s Second LawThe unbalanced force acting on an object equals the object’s mass times its accelerationNet force equals mass times accelerationF = maUnbalanced force on an object determines how much an object speeds up or slows down
9Newton’s Second LawForce is measured in Newtons ( 1 N = 1 kg x 1 m/s2 )For equal forces, a larger mass accelerates lessAcceleration depends on force and mass
10Newton’s Second LawForce is measured in Newtons ( 1 N = 1 kg x 1 m/s2 )For equal forces, a larger mass accelerates lessAcceleration depends on force and mass
111 – Newton’s 1st and 2nd Laws Key Questions:What makes an object speed up, slow down, or change directions?What determines how much an object speeds up or slows down?
12Bellwork What is Newton’s First Law (in your own words) What is Newton’s Second Law (in your own words)
132 – Gravity Key Questions: How are weight and mass related? Why do objects fall to the ground when dropped?What is the relationship between free-fall acceleration and mass?Why does a projectile follow a curved path?
14Weight and Mass Force on an object due to gravity is WEIGHT Weight is measured in NewtonsFree-fall acceleration is a constant acceleration all objects on earth experienceWeight is equal to mass times free-fall accelerationw = mg
15Law of Universal Gravitation All objects in universe attract each other through the force of gravity𝑭=𝑮 𝒎 𝟏 𝒎 𝟏 𝒅 𝟐
16Law of Universal Gravitation All matter is affected by gravityGravitational force increases with mass OR decreases with distance
17Free FallWithout air resistance, all objects falling near Earth’s surface accelerate at the same rate regardless of their massDue to the Law of GravitationAir resistance can balance weightEXAMPLE : Leaf falling at constant velocityTERMINAL VELOCITY ( max velocity obtained )
18Projectile MotionCurved path of an object thrown, launched, kicked, or otherwise projected near Earth’s surface
19Projectile Motion Two components – horizontal and vertical Curved path when both are combined
212 – Gravity Key Questions: How are weight and mass related? Why do objects fall to the ground when dropped?What is the relationship between free-fall acceleration and mass?Why does a projectile follow a curved path?
22BellworkWhat is the difference between weight and mass?
233 – Newton’s Third Law Key Questions: What happens when an object exerts a force on another object?How do you calculate the momentum of an object?What is the total momentum after objects collide?
24Action and Reaction Forces Foot on Ball – ACTIONBall on Foot – REACTION
25Newton’s Third LawFor every ACTION force there is an opposite and equal REACTION force
26Newton’s Third Law Forces always occur in pairs Forces in a force pair do not act on the same objectDo not cancel each otherEqual forces do not always have equal effects
27QuickLab – Action/Reaction Forces Hang a 2 kg mass from a spring scaleObserve and record the reading on the spring scaleWith the mass on the first scale, link a second scale to the firstObserve/record readings from both scales
28QuickLab – Action/Reaction Forces QUESTIONS:What are the action and reaction forces in the spring scale-mass system that you have constructed?How did the readings on both scales compare in the last step? Explain how this demonstrates Newton’s 3rd Law?
29Momentum A property of all moving objects Along a straight line, momentum is the product of an object’s mass and velocityp = mvIncreases as mass and velocity increasesForce is related to change in momentumHow does moving the catcher’s glove back change the force needed to stop the ball?
30Conservation of Momentum The total amount of momentum in an isolated system is conservedTotal momentum of two or more objects after a collision is the same as the momentum beforeExplained by 3rd Law