1 / 57

Force and Motion

flint
Download Presentation

Force and Motion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Force and Motion 8th Grade Science Instructor: Magee

    2. Warm Up: Rolling Marbles 3.9.71 Five friends built a marble tower. The track was designed so that the marbles would move down the track in a circular path. The track ended on the floor. Each friend predicted how he or she thought the marble would move when it rolled off the end of the track onto the floor. This is what they said. Magda: I think it will roll in circles. Soledad: I think it will curve for a bit and then straighten out. Allen: I think it will roll in one big curve. Keira: I think it will roll in a straight line. Rafael: I think it will zigzag for a little while.

    3. Warm Up: The Drop 3.10.77 Randy has three different types of balls. Each ball is about the same size. Ball 1 is a wooden ball. It’s mass is 28g. Ball 2 is a golf ball. Its mass is 46g. Ball 3 is a metal ball. Its mass is 110g. Randy held his arm out and dropped the three balls at the same time from the same height. In what order will the balls hit the floor? Prediction A: Ball 1, then Ball 2, then Ball 3 Prediction B: Ball 3, then Ball 2, then Ball 1 Prediction C: Ball 2, then Ball 3, then Ball 1 Prediction D: All three balls will hit the floor at about the same time. Prediction E: Ball 3 will hit first, followed by Ball 1 and Ball 2 hitting the floor at the same time

    4. Warm Up: Apple on a Desk 3.8.63 Mrs. Canales pointed to an apple sitting on her desk. She asked her students to describe any forces acting on the apple. This is what some of her students said. Which student do you most agree with? Explain your answer. Archie: The only force acting on the apple is air pressure. Sam: There is one force acting on the apple. Gravity is the force that pulls on the apple. Soledad: There are two forces: the desk pushes up on the apple and gravity pulls downward on the apple. Misha: There are many forces acting on the apple; but it is the holding force in the apple that keeps it on the desk. Tess: There are no forces acting on the apple because the desk stops any forces from acting on it.

    5. Warm Up: Standing on One Foot Mario stood on his bathroom scale with two feet. He read his weight on the scale. He then lifted one foot. Circle what you think happened to the reading on the scale when he stood on one foot. It showed an increase in weight It showed a decrease in weight His weight stayed the same

    6. Warm Up At Forks High School, a particular science class is studying force and motion. They are very excited about this unit. During a class discussion this question is posed, “How do unbalanced forces cause changes in the speed or direction of an object’s motion?” Read the responses and choose the one that you think is correct. Describe why you chose that answer. Bella: Unbalanced forces cause changes in the speed of an object’s motion because they can overpower gravity. Jasper: Unbalanced forces cause changes in an object’s motion because they are equal in magnitude and opposite in direction. Alice: Unbalanced forces cause changes in an objects motion because they transfer energy. Edward: Unbalanced forces are able to alter an object’s motion because the forces are not equal.

    7. Warm Up: Matching ____Kinetic ____Centripetal ____Mass ____Acceleration ____Velocity ____Weight ____Gravity ____Inertia ____Speed ____Momentum ____Newton Amount of matter in an object Amount of force exerted on an object due to gravity Distance covered per unit of time Rate at which velocity changes over time Speed in a given direction Unit of measurement for force Energy of motion Tendency of a moving object to keep moving Depends on the mass and velocity of an object Type of force that keeps objects moving in a circle Attractive force between two objects

    11. You will need these formulas to answer the speed and velocity problems. Write them down in your interactive notebook. Speed=distance/time Velocity=distance/time (in a specific direction)

    12. Determining Speed (Velocity) What is the velocity of a car that traveled a total of 75 kilometers north in 1.5 hours? What is the velocity of a plane that traveled 3000 miles from New York to California in 5 hours? John took 45 minutes to bicycle to his grandmother’s house, a total of four kilometers. What was his velocity in km/hr? It took 3.5 hours for a train to travel the distance between two cities at a velocity of 120km/hr. How many km lie between the two cities? How long would it take for a car to travel a distance of 200 km if it is traveling at a velocity of 55 km/hr? A car is traveling at 100km/hr. How many hours will it take to cover a distance of 750 km? A plane traveled for about 2.5 hours a velocity of 1200 km/hr. What distance did it travel? A girl is pedaling her bicycle at a velocity at .10 km/min. How far will she travel in two hours? An ant carries food at a speed of 1 cm/s. How long will it take the ant to carry a cookie crumb from the kitchen table to the ant hill a distance of 50m? Express your answer in 3 ways seconds, minutes, and hours. The water in the Buffalo River flows at an average speed of 5 km/hr. If you and a friend decide to canoe down the river a distance of 16 kilometers, how many hours and minutes will it take? Name(s) _______________________________________________________________________ Show your work on the back

    13. Determining Speed (Velocity) What is the velocity of a car that traveled a total of 75 kilometers north in 1.5 hours? 50km/hr What is the velocity of a plane that traveled 3000 miles from New York to California in 5 hours? 600 mi/hr John took 45 minutes to bicycle to his grandmother’s house, a total of four kilometers. What was his velocity in km/hr? 5.3km/hr It took 3.5 hours for a train to travel the distance between two cities at a velocity of 120km/hr. How many miles lie between the two cities? 420 How long would it take for a car to travel a distance of 200 km if it is traveling at a velocity of 55 km/hr? 3.6hr A car is traveling at 100km/hr. How many hours will it take to cover a distance of 750 km? 7.5hr A plane traveled for about 2.5 hours a velocity of 1200 km/hr. What distance did it travel? 3000km A girl is pedaling her bicycle at a velocity at .10 km/min. How for will she travel in two hours? 12km An ant carries food at a speed of 1 cm/s. How long will it take the ant to carry a cookie crumb from the kitchen table to the ant hill a distance of 50m? Express your answer in 3 ways seconds, minutes, and hours. 5000s, 83.3min, 1.39hr The water in the Buffalo River flows at an average speed of 5 km/hr. If you and a friend decide to canoe down the river a distance of 16 kilometers, how many hours and minutes will it take? 3hrs, 12min

    14. Calculating Average Speed Part I Average speed= total distance/total time. Graph the following data on the grid and answer the questions that follow.

    15. Calculating Average Speed Part II Name: Average Speed = Total Distance/ Total Time What is the average speed after two minutes? After three minutes? After five minutes? What is the average speed between two and four minutes? What is the average speed between four and five minutes?

    16. Calculating Average Speed Part I Graph the following data on the grid and answer the questions that follow.

    17. Calculating Average Speed Part II Average Speed = Total Distance/ Time What is the average speed after two minutes? 37.5 m/min After three minutes? 30m/min After five minutes? 25 m/min What is the average speed between two and four minutes? 17.5 m/min What is the average speed between four and five minutes? 15 m/min

    20. Acceleration Calculations Acceleration means a change in speed or direction. It can also be defined as a change in velocity per unit of time. A= vf-vi/t Where a=velocity, vf=final velocity, vi=initial velocity, t=time A car accelerates from a standstill to 60km/hr in 10 seconds. What is the acceleration? A car accelerates from 25km/hr to 55km/hr in 30 seconds. What is its acceleration? A train is accelerating at a rate of 2 km/hr/s. If its initial velocity is 20km/hr, what is its velocity after 30 seconds? A runner achieves a velocity of 11.1m/s 9s after he begins. What is his acceleration? What distance did he cover?

    21. Acceleration Calculations Acceleration means a change in speed or direction. It can also be defined as a change in velocity per unit of time. A= vf-vi/t Where a=velocity, vf=final velocity, vi=initial velocity, t=time A car accelerates from a standstill to 60km/hr in 10 seconds. What is the acceleration? 6km/hr/s A car accelerates from 25km/hr to 55km/hr in 30 seconds. What is its acceleration? 1km/hr/s A train is accelerating at a rate of 2 km/hr/s. If its initial velocity is 20km/hr, what is its velocity after 30 seconds? 80km/hr/s A runner achieves a velocity of 11.1m/s 9s after he begins. What is his acceleration? What distance did he cover? 1.2m 100m

    22. Checkpoint How do you know when an object is in motion? How do balanced forces affect an object’s motion? How do unbalanced forces affect an object’s motion? What is the relationship between work and energy? How are speed, velocity and acceleration similar? How are they different?

    23. Graphing Speed vs. Time Plot the following data on the graph and answer the questions.

    24. Graphing Speed vs. Time Pt.2 As time increases, what happens to the speed? What is the speed at 5 s? Assuming constant acceleration, what would be the speed at 14 s? At what time would the object reach a speed of 45 km/hr? What is the object’s acceleration? What would the shape of the graph be if the speed of 50.0 is maintained from 10s to 20s? Based on the information in Problem 6, calculate the acceleration from 10 s to 20 s. What would the shape of the graph be if the speed of the object decreased from 50km/hr at 20s to 30km/hr at 40s? What is the acceleration in Problem 8?

    25. Graphing Speed vs. Time Plot the following data on the graph and answer the questions.

    26. Graphing Speed vs. Time Pt.2 As time increases, what happens to the speed? increases What is the speed at 5 s? 25km/hr Assuming constant acceleration, what would be the speed at 14 s? 70km/hr At what time would the object reach a speed of 45 km/hr? 9s What is the object’s acceleration? 5km/hr/s What would the shape of the graph be if the speed of 50.0 is maintained from 10s to 20s? Horizontal line Based on the information in Problem 6, calculate the acceleration from 10 s to 20 s. 0km/hr/s What would the shape of the graph be if the speed of the object decreased from 50km/hr at 20s to 30km/hr at 40s? \ What is the acceleration in Problem 8? -1km/hr/s

    29. Force Force a push or pull

    30. Friction Four Types of Friction Static Friction – force that acts on objects that are not moving. (Couch Potato) Sliding Friction - force that opposes the direction of motion of an object as it slides over a surface. (Ice skating or bobsledding) Rolling Friction – friction force that acts on rolling objects. (Rollerblading) Fluid Friction – force that opposes the motion of an object through a fluid. (Planes flying or submarines traveling)

    31. Gravity Gravity force of attraction between any two objects in the universe increases as... mass increases distance decreases

    32. Gravity Who experiences more gravity - the astronaut or the politician?

    33. Gravity Would you weigh more on Earth or Jupiter?

    34. Newton’s First Law Newton’s First Law of Motion An object at rest will remain at rest and an object in motion will continue moving at a constant velocity unless acted upon by a net force.

    35. Newton’s First Law Newton’s First Law of Motion “Law of Inertia” Inertia tendency of an object to resist any change in its motion increases as mass increases

    36. Newton’s Second Law Newton’s Second Law of Motion The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

    37. Newton’s Second Law

    38. Calculations

    39. Calculations

    40. Calculations

    41. Newton’s Third Law Newton’s Third Law of Motion When one object exerts a force on a second object, the second object exerts an equal but opposite force on the first.

    42. Newton’s Third Law Problem:

    43. Newton’s Third Law forces are equal and opposite but act on different objects they are not “balanced forces” the movement of the horse depends on the forces acting on the horse

    44. Newton’s Third Law Action-Reaction Pairs

    45. Newton’s Third Law Action-Reaction Pairs

    46. Newton’s Third Law Action-Reaction Pairs

    47. Momentum Momentum quantity of motion

    48. Momentum

    49. Momentum

    50. Conservation of Momentum Law of Conservation of Momentum The total momentum in a group of objects doesn’t change unless outside forces act on the objects.

    51. Conservation of Momentum Elastic Collision KE is conserved

    52. Conservation of Momentum

    53. Conservation of Momentum

    54. Conservation of Momentum

    55. Universal Forces Electromagnetic Forces – are associated with charged particles. The only force to attract and repel.

    56. Universal Forces Nuclear Forces – act within the nucleus of an atom to hold it together, strong and weak.

    57. Universal Forces Gravitational Forces – attractive forces that act between any two masses. “Every object in the universe attracts every other object.” – Newton’s Law of Universal Gravitation.

    58. Centripetal Force Centripetal force is a center-directed force that continuously changes the direction of an object to make it move in a circle. This explains how the moon and satellites stay in orbit

More Related