Newton’s Laws



Newton’s LawsNotes & Homework PacketNewton’s Laws Learning Targets0I know nothing about this target1 (Beginning)I have a very basic understanding of this target.2 (Developing)I can complete this target with help.3 (Progressing)I will be ready to be assessed on this target with a little more practice.4 (Mastered)I am ready to be assessed on this target and fully understand itLearning TargetDate(s)My Present Understanding1st encounter = circle,2nd encounter = square,3rd encounter = triangle1I can define and identify forces.0 1 2 3 42I can define Newton's 1st Law, apply it to real life examples, and know its relationship to inertia.0 1 2 3 43I can explain the difference between and calculate mass and weight.0 1 2 3 44I can draw and analyze accurate force diagrams.0 1 2 3 45I can calculate and explain net force.0 1 2 3 46I can describe and use Fnet = ma conceptually and mathematically, including the inverse and direct relationship.0 1 2 3 47I can define and apply terminal velocity.0 1 2 3 48I can solve for either ?, FF or FN using ? = FF/FN.0 1 2 3 49I can describe what affects the coefficient of friction and frictional force.0 1 2 3 410I can apply Newton's 3rd Law to real life and identify examples.0 1 2 3 4Variables: WordSymbolDefinitionForceMassAccelerationWeightCoefficient of FrictionFrictional ForceNormal ForceNewton’s 1st Law of Motion NotesNewton’s First Law applies to both object ___ __________ and ___ ___________.Newton’s First Law says____________________________________________________________________________________________________________________________________________________________________________________________________Newton’s First Law is also called the Law of ____________. ____________ describes the tendency for an object to resist change in ____________.Force NotesA force is:________________________________________________________________________________________________________________________________________________Examples of forces:English Units for Measuring Force:Metric units for Measuring Force:Tool used to Measure Force:Different types of forces:Friction –Air Resistance –Buoyant Force –Gravity – Normal Force –Newton’s First Law WorksheetAn elephant and a mouse would both have a weight of zero Newtons in gravitational-free space; however, they would still retain their “amount of matter” also known as __________. If they were moving toward you with the same speed, would they bump into you with the same effect? Why?The law of inertia states that no force is required to maintain motion. Why then do you have to keep pedaling a bicycle to maintain motion?You place a basketball in the back of a pick-up truck and then accelerate the truck quickly. Describe the motion of the ball relative to (a) the ground and (b) the truck.Many automobile passengers have suffered neck injuries when struck by cars from behind. How does Newton’s first law of inertia apply here?How do headrests help guard against this type of injury?In the cabin of a jetliner that cruises at 600km/hr, a pillow drops from an overhead bin to your lap below.Since the jetliner is moving so fast, why doesn’t the pillow slam into the rear of the plane when it drops?What is the horizontal speed of the pillow relative to the ground?What is the horizontal speed of the pillow relative to you inside the jet?If an elephant were chasing you, its enormous mass would be most threatening, but if you zigzagged while it followed you, the elephant’s mass would be to your advantage. Why?An insect is buzzing along when the windshield of a car slams into it. What happens to the motion of the insect? Explain in terms of Newton’s First Law.Two closed containers look the same, but one is packed with lead and the other with a few feathers. How could you determine which had more mass if you and the containers were in a weightless condition in outer space?If you were in a spaceship and fired a 1000kg probe into frictionless space, how much force would have to be exerted on the probe to keep it going for 1000 years?If the head of a hammer is loose, why does pounding it handle first rather than head first work better for tightening it?A head-on collision occurs between a Mack truck loaded with gold and a Moped. The truck’s velocity decreases by 25km/h, while the Moped’s velocity changes from 75km/h to -75km/h,Which vehicle has the greater inertia?Why does the forward motion of the truck continue?If the collision would have been between two similar Mopeds, how would the outcome be different?How does the combination of a seat belt and an airbag help prevent injury in a head on collision?A 7,434,342kg meteorite slams into Mt. Everest at five times the speed of sound (that’s fast!). Why doesn’t Mt. Everest move?Conceptual Physics - Concept DevelopmentNewton’s 1st LawAdapted from Conceptual Physics Concept Development Practice Page #11Directions: Circle the correct answer.An astronaut in outer space away from gravitational or frictional forces throws a rock.The rock will…Gradually slow to a stop.Continue moving in a straight line at a constant speed.The rock’s tendency to do this is called…InertiaWeightAcceleration443484017145The sketch to the right shows a top view of a rock being whirled around at the end of a string (clockwise). If the string breaks, the path of the rock would be…ABCDSuppose you are standing in the aisle of a bus that travels a straight road at 100km/h, and you hold a pencil still above you head. Relative to the bus, the velocity of the pencil is 0km/h. Relative to the road, the pencil has a horizontal velocity of…Less than 100km/h100km/hMore than 100km/hSuppose you release the pencil. While it is dropping, and relative to the road, the pencil has a horizontal velocity of…Less than 100km/h100km/hMore than 100km/hThis means that the pencil will strike the floor of the bus at a place directlyBehind youAt your feet below your handIn front of youRelative to you, the way the pencil drops,Is the same as if the bus were at restDepends on the velocity of the busHow does this example demonstrate the law of inertia?571500-1143005029200-114300Mass versus WeightMassDefinition:Units:Your mass on the Earth:Process to convert from weight to massEquation:Your mass on the moon:Your mass in outer space:WeightDefinition:Units:Your weight on Earth:Process to convert from mass to weightEquation:Your weight on the moon:Your weight in outer space:Weight Practice ProblemsImportant values:gearth = 9.8m/s2gmars = 3.8m/s2gjupiter = 26.6m/s2On Earth, an astronaut steps on a scale that says 83kg.What is her mass on Earth? 4781550-1905What is her weight on Earth?4809490172720What is her weight on Mars?What is her mass on Mars?What is her weight on Jupiter?4814570138430What is her mass on Jupiter?Anticipation Guide to Newton’s 2nd Law ReadingDirections: Read the statements below before reading chapter/section 4.6-4.7, 5.1-5.7 in the Conceptual Physics textbook. In the blank provided write whether you think the statement is true or false. Then, read the text. After reading the text, provide the appropriate true or false response to the statement. If you mark a statement to be false, rewrite the statement so that it is true. Be prepared to defend your answer in class.Before AfterReadingReading______________Acceleration is the change in distance per certain time interval.______________Forces are what cause things to continue moving at a constantspeed - even in frictionless environments.______________The combination of all the forces that act on an object is called the gross force.______________Force and acceleration are inversely related.______________Acceleration and mass are inversely related.______________Another name for the force that supports a book on a table is the irregular force.______________When you sit on a swing, each chain exerts a force that is equal to your weight.______________When an object has a net force of zero, it is accelerating.______________The earth pulls on more massive objects with a larger force than less massive objects. ______________The previous statement proves that more massive objects fall faster than less massive objects.______________More massive objects have more inertia and will be less responsiveto gravity than less massive objects.______________The previous statement proves that less massive objects fall faster than more massive objects.______________Terminal velocity is when an object reaches the fastest speed that it can while falling through the atmosphere.Newton’s 2nd Law NotesNewton’s Second Law describes the relationship between _________________, _______________, and _______________.Force and ________________ are directly related. If mass is kept the same, when _________________ increases, then acceleration __________________. Also, if one decreases the other _______________.Acceleration and mass are ________________ related. If force is kept constant, when mass increases, then acceleration ________________. On the other hand, when mass decreases, acceleration ________________. Newton’s Second Law can be summarized with the following equation:Net force is ________________________________________________________.For example: If Mary pushes on a box with a force of 5N forward and Polly pushes on the same box with a force of 6N in the opposite direction, what is the net force?Net force = F1 + F2Net force = 5N + -6NNet force = -1N400050015621012N12N12N8N0012N12N12N8NFind the Net Force in both the horizontal and vertical planes for the following figure:Terminal Velocity is _________________________________________________ __________________________________________________________________.Terminal velocity occurs when ____________________________________ _____________________________________________________________.Force DiagramsIn physics, we use force diagrams to visually describe the forces acting on a given object. They give a picture of the net force on an object, and, when drawn correctly, show the direction an object will accelerate. We always draw forces as vectors from the object’s center of mass. For example, the force diagram for an object falling toward the Earth would look like…FgravityObject’s center of massFgravityObject’s center of massDraw force diagrams for the following objects:1. A person with a parachute falls at towards the earth after jumping from a plane. What forces are acting on the parachuter? (List them and draw the force diagram)37719001016002. A duck floats on water. What forces are acting on it? (List them and draw the force diagram).36099751625603. Draw a force diagram representing the forces acting on a car driving down the road.316992039370004. Draw a force diagram representing the forces acting on an airplane in the air.34290001625605. Draw a force diagram representing the forces acting on a boat crossing the ocean.37719001962154114800295910006. Draw a force diagram representing the forces acting on a bungee jumper at the end of his rope.7. Draw a force diagram representing the forces acting on a bicycle being pedaled:3886200194945361569027368500Net Force ProblemsDetermine the net force (magnitude and direction) acting on each of the objects shown in the diagrams below. Be sure to state both horizontal and vertical net force when applicable.18669005845175e.00e.195897560737750018669003254375c.00c.195897534829750046704251090930b.00b.476250013195300018510251090930a.00a.194310013195300012N12N12N12N12N5N7N12N12N5Nd.12N7N7N5N5N7N12N15Nf.12N12N12N12N12N5N7N12N12N5Nd.12N7N7N5N5N7N12N15Nf.Terminal VelocityWhen an object falls towards the Earth, what forces are acting on it?355981043815Weight of skydiver = 500 N#1 Skydiver just jumps out of planeForce of gravity = _____________Air resistance = 0NMotion of skydiver:#2 Skydiver begins fallingForce of gravity = _____________Air resistance = 250NMotion of skydiver:#3 Skydiver is fallingForce of gravity = _____________Air resistance = 500 NMotion of skydiver:#4 Skydiver opens parachuteForce of gravity = _____________Air resistance = 750NMotion of skydiver:00Weight of skydiver = 500 N#1 Skydiver just jumps out of planeForce of gravity = _____________Air resistance = 0NMotion of skydiver:#2 Skydiver begins fallingForce of gravity = _____________Air resistance = 250NMotion of skydiver:#3 Skydiver is fallingForce of gravity = _____________Air resistance = 500 NMotion of skydiver:#4 Skydiver opens parachuteForce of gravity = _____________Air resistance = 750NMotion of skydiver:Now consider an object falling towards the ground:-39624014033500346710017145000Terminal Velocity is:Terminal Velocity occurs because:How can the terminal velocity of an object (like a falling person) be modified?Use the graph below describing the motion of a skydiver’s motion to answer thequestions that follow.1600200160655a. When does the sky diver reach terminal velocity?b. What is the skydiver’s terminal velocity?c. What likely event caused the change in speed between 39 and 45 seconds?d. What is likely happening from 45-52 seconds?Conceptual Physics - Concept DevelopmentNewton’s 2nd LawAdapted from Conceptual Physics Concept Development Practice Page #12Use the words mass, weight and volume to complete the table.The force due to gravity on an objectThe quantity of matter in an objectThe amount of space an object occupiesDifferent masses are hung on a spring scale calibrated in Newtons. The force exerted by gravity on 1 kg = 9.8NThe force exerted by gravity on 5 kg = _______NThe force exerted by gravity on _______kg = 98NMake up your own mass and show the corresponding weight.The force exerted by gravity on ______kg = ______NBy whatever means (spring scales, measuring balance, etc.), find the mass of your physics book. Then complete the table below.ObjectMassWeightMelon1 kgApple1 NPhysics BookUncle Harry90 kgNewton’s Law’s HomeworkDefinitions: Direct Relationship: If one variable increases, the other variable increases as well. If one variable decreases, then the other variable also decreases.Indirect/Inverse Relationship: If one variable increases, the other variable decreases. If one variable decreases, then the other variable increases.Directions: Show all work and include units on all values.If you increase the mass of an object, while keeping the force constant, the object’s acceleration will ___________________.If you increase the force applied to an object, while keeping the mass constant, the object’s acceleration will ___________________.What type of relationship exists between force and mass?What type of relationship exists between force and acceleration?What type of relationship exists between acceleration and mass?If a 2kg mass is accelerating at a rate of 2m/s2 on a frictionless surface, how much force is acting on the mass?A 2000kg pickup truck can accelerate uniformly at 4m/s2. How much of the engine’s force accelerates the truck?What is the acceleration, if the truck is now pulling a 1000kg boat and trailer and the engine applies the same force as in step 7a?A 40kg sprinter starts from rest and 2.0s later is running at 8.0m/s. What is the average horizontal force acting on her?A student pushes a cart with 42N of force and the cart accelerates at 2.5m/s2. What is the mass of the cart?A 22N force is constantly acting on a 10kg cart located on a horizontal table. If there is a constant frictional force of 2N,What is the net force acting on the cart?What is the cart’s acceleration?How fast is the cart going after 4.0s?What is the net force when a person is pushing a cart with a force of 60N while her friend applies a force of 55N in the opposite direction?What is the net force acting on an object that is falling and has reached terminal velocity?If the net force acting on an object is 7N and the weight of the object is 50N.What is the mass of the object?What is the acceleration of the object?A child pulls an 8.5kg wagon with a force of 12N. If the frictional force on the cart is 9N, what is the acceleration of the wagon?A person rides a cart that is being pushed by a friend. If the person and the cart accelerate at 0.3m/s2 and the friend pushes with a force of 25N, what is the combined mass of the student and the cart? (Neglect friction.)A person rides a cart that is being pushed by a friend. If the person and the cart accelerate at 0.6m/s2 and the friend pushes with a force of 27N, if the frictional force is 4N, what is the combined mass of the student and the cart?Two 5N forces are acting due west on an object while another force of 3N acts due east. What is the acceleration of the object if it has a mass of 4kg?Notes for That Mu That You DoESPN Sports Figures Video NotesThe friction in the _________________ slows a NASCAR car down.Friction with the air _____________________ in a NASCAR car.Friction helps the NASCAR car by:1.2. Sled Example:What two factors are demonstrated to affect the friction necessary to move the sled in the video?1. 2. In physics, the number to describe the amount of frictional force between two surfaces is ______________________________ and is represented with the Greek symbol _______.Sneaker Example:A sneaker and the racetrack have a _____________ coefficient of friction.A dress shoe and the racetrack have a _____________ coefficient of friction.Static friction is the frictional force while an object is stationary; the ________________ friction is the frictional force while an object is sliding.Static friction is always ______________ than kinetic friction.Tire Example:The two factors that affect the coefficient of kinetic friction are _________ (we call this Normal Force) and the force that it takes to slide the tire across the track (at a constant speed).In the video, the weight (normal force) was _____________ and the force to slide it across the track was ____________.Friction ProblemsDirections: Show all work and include units on all values.You pull a shoe with 12N of force across a wooden floor at a constant velocity. What is the coefficient of friction if the shoe and the mass in the shoe have a weight of 16N?You push a 60kg rock across the floor, where there is a coefficient of friction of 0.4 between the rock and the floor.What is the weight of the rock?What is the normal force acting on the rock?What is the frictional force acting on the rock?If you were to take the rock from #2 and push with more force than the frictional force…What type of motion would the rock undergo?What would be the net force acting on the rock if you push with a force of 350N?What is the acceleration of the rock?Name: ____________________________Net Force & Friction ProblemsDirections: When even minimal mathematical work is required show ALL work. Draw a force diagram for each problem.A force of 50N is used to drag a 10kg box across a horizontal table to the right. If a frictional force of 15N is applied to the box….Draw a force diagram of the box to the right.Calculate the net force on the box.Calculate the acceleration of the box.Calculate the weight of the box.Calculate the coefficient of friction.A horizontal force of 15N pulls a 5kg block along a horizontal surface. If the force produces an acceleration of 2m/s2…Draw a force diagram of the box to the right.What is the net force acting on the block?Calculate the frictional force acting on the block.Calculate the weight of the block.Calculate the coefficient of friction.A 2kg mass moving along a horizontal surface at a constant velocity is acted upon by a 5N force of friction. Draw a force diagram of the mass to the right.What is the net force on the mass?What is the acceleration of the mass?Calculate the weight of the mass.Calculate the coefficient of friction.A force of 40N applied horizontally is required to push a 20kg box at a constant speed across the floor. Draw a force diagram of the box to the right.What is the acceleration of the box?What is the net force acting on the box?Calculate the weight of the box.Calculate the coefficient of friction.An 80kg person slides along the ground. Assume the coefficient of kinetic friction is 0.30.Draw a force diagram of the person to the right.What is the weight of the person?What is the frictional force acting on the person?If the person is not being pushed and is just slowing down, what is the net force acting on the person?What is the acceleration of the person?Newton’s 3rd Law NotesNewton’s 3rd Law says:________________________________________________________________________________________________________________________________________________What does Newton’s 3rd Law mean?Action and Reaction forces come in pairs:I push on desk, _____________________Car pushes on road, __________________Bird pulls on worm, ___________________Why is Newton’s 3rd Law helpful?Swimmer:Bird:Car driving down road:Practice:I push east on a wall with a force of 20N. What is the magnitude and direction of the reaction force?A mosquito flies along and runs into the windshield of rapidly moving vehicle. Which force is stronger, the force of the windshield hitting the mosquito or the force of the mosquito hitting the windshield? Explain.Practice with Newton’s 3rd Law1. Complete the following Action/Reaction pairs:a. A tennis ball pushes a racket, ___________________________________________b. Cue ball (moving) pushes 8-ball which was at rest, __________________________c. Golf club strikes ball, _________________________________________________d.Weightlifter pushes up on dumbbell, _____________________________________Bowling ball pushes pin, ______________________________________________f.Gravity due to earth pulls ball to the ground,_______________________________2. Identify 6 Action/Reaction pairs in the diagram below:1187450152400a. ___________________________________________________________________b.___________________________________________________________________c.___________________________________________________________________d.___________________________________________________________________e.___________________________________________________________________f.____________________________________________________________________3. Would it be possible to hold a sheet of paper in the air and have the strongest man in the world to strike it with a force of 500N? Why or why not?4.Which force is stronger, the force exerted on the bullet as it leaves a rifle, or the force exerted on the shoulder by the rifle as it kicks back? Why?5.Things get a bit heated in the hallway. Jake sticks out his arm and pushes on Sam. The conflict stops immediately thereafter. The security guard wanders by and writes a behavior report. He notes that Sam pushed Jake. Is the behavior report correct? Why or why not?6.You are free-floating in outer space at a complete standstill. Your jet propeller just ran out of gas. The space shuttle is 20m away and no one else is inside. For a brief moment you panic and fear all is lost. Then suddenly you remember the wonderful lessons taught by your brilliant physics teacher. Although it once seemed strange that you were carrying a bowling ball with you in outer space you are now thankful it is with you. How can the bowling ball and Newton get you out of this jam?7.A farmer has just loaded up her cart with all sorts of vegetables grown her farm. She hooks the donkey to the cart and says GIDDYAP! However, the donkey was watching a little Bill Nye and thought he knew Newton’s 3rd law. He says to the farmer: “It won’t do no good to have me pull on this cart. If I pull on the cart, it’s just gonna pull me with an equal force in the opposite direction. We won’t get anywhere.” What can the farmer tell the donkey to convince it that it can pull the cart along the ground? So You Think You Know Newton?center175895Identify whether the following is an example of Newton’s 1st, 2nd or 3rd Law.___ When a car runs into a post, the passengers continue forward.___ When you stand on a skateboard and push backwards on the wall, you goforward.___ It takes 4 times more force to push me at 2m/s2 on a skateboard than a child.___ When an inflated balloon is released, it flies forward.___ I can pull a tablecloth out from underneath a place setting.___ When I am standing at a stoplight and my car gets hit from behind, my cup of hotapple cider that I just put on the dashboard falls off the dashboard and lands on my seat.___ A guy breaks his hand by punching a wall.___ Your car does not accelerate as well when you attach a trailer with a motorboat.___ When I quickly pull a produce bag off the large roll at the grocery store, the rolldoes not move.Appendix:Newton’s 1st Law DemosFor each demo that you see…record what happened why it happened how it relates to the 1st lawDemoWhat Happened?Why did this happen?How does this demo support Newton’s 1st Law?Physics 1 Equation Sheetafall = 9.8m/s2Motion UnitNewton’s Law Unita=Fnetmweight = mgμ= FfFNFluid Force UnitWork, Energy, Power & Simple Machines UnitWaves Unitssound in air = 331m/s + 0.6*(#?C above 0)Electricity UnitConversion SheetDistance1,000,000 micrometers = 1 meter1,609.3 meters = 1 mile5,280 feet = 1mile3 feet = 1 yard12 inches = 1 foot2.54 centimeters = 1 inchMass and Weight28.4 grams = 1 ounce2.2 pounds = 1 kilogram1 pound = 4.45 NewtonsTime60 seconds = 1 minute60 minutes = 1 hour3,600 seconds = 1 hour24 hours = 1 day7 days = 1 week365.24 days = 1 yearArea640 acres = 1 square mileVolume3.79 liters = 1 gallon1 cm3 = 1mLPressure14.7 lbs/in2 = 1 atm1.01 x 105 N/m2 = 1 atm101 kPa = 1 atmEnergy & Power4.184 J = 1 cal746 W = 1 hpSpeed1.15 mi/h = 1 knotDensityDwater = 1 g/mL = 1kg/L ................
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