Slide 1 / 120 Slide 2 / 120 8th Grade Forces and Motion Classwork-Homework Slides www.njctl.org Slide 3 / 120 Slide 4 / 120 1 Define motion. Classwork #1: Motion and Speed Slide 5 / 120 Slide 6 / 120 2 When you look at the ground you seem to be at 3 Define speed. rest. Why is this? Why does someone in space see you moving in a circle?
Slide 7 / 120 Slide 8 / 120 4 What is the formula for measuring the speed of an 5 Lance Armstrong can ride his bicycle at speeds of 15 m/s. If he is traveling at this speed, how long object? will it take him to travel 81.9 meters? Show your work. Slide 9 / 120 Slide 10 / 120 John is growing another crop of corn this year. He Julia is learning how to ride her tricycle. It takes 6 7 plows a row of his field in 90 seconds. If each row her 10 seconds to go from one end of the is 384 meters long, how fast does John drive his driveway to the other. If she travels at 3 m/s, how tractor? Show your work. far does she travel? Show your work. Slide 11 / 120 Slide 12 / 120 8 How can you tell that an object is in motion? Homework #1: Motion and Speed
Slide 13 / 120 Slide 14 / 120 9 What is a frame of reference? 10 How long does it take a snail to travel a distance of 3 ft at 0.1 ft/sec? Show your work. Slide 15 / 120 Slide 16 / 120 How far does a cat run if it travels at a speed of 3 A racecar driver frequently drives her racecar at 11 12 m/s for 25 seconds? Show your work. 67 m/s for as long as she can. If she drives her car at that speed for 22 seconds, how far will she travel? Show your work. Slide 17 / 120 Slide 18 / 120 13 Everyone in Paperville needs their newspaper before 6 a.m. on Monday. If it takes the delivery boy 3 hours to deliver the papers at 12 m/s, what is the distance of the paper route in Paperville? Show your work. ( HINT: convert 3 hours to Classwork #2: Speed and Velocity seconds before using the speed equation )
Slide 19 / 120 Slide 20 / 120 Time (s) Name Country Date The 100m dash is a sprint race in track and field 9.572 Usain Bolt Jamaica August 16, 2009 competitions where athletes are timed on how long it takes them to sprint a distance of 100m. It has been an 9.683 Usain Bolt Jamaica August 16, 2008 Olympic sport since 1896. The table below shows 9.72 Usain Bolt Jamaica May 31, 2008 some of the record setting times achieved by athletes 9.74 Asafa Powell Jamaica September 9, 2007 running the 100m dash. Use the data table to answer 9.762 Asafa Powell Jamaica August 18, 2006 the questions. 9.763 Asafa Powell Jamaica June 11, 2006 9.766 Justin Gatlin USA May 12, 2006 9.768 Asafa Powell Jamaica June 14, 2005 9.78 Tim Montgomery USA September 14, 2002 9.79 Maurice Green USA June 6, 1999 9.835 Donovan Bailey Canada July 27, 1996 9.85 Leroy Burrell USA July 6, 1994 9.86 Carl Lewis USA August 25, 1991 9.90 Leroy Burrell USA June 14, 1991 9.92 Carl Lewis USA September 24, 1988 Slide 21 / 120 Slide 22 / 120 14 According to the table, who holds the current 15 By how much time did Tim Montgomery beat the world record for finishing the 100 m sprint the previous world record holder? fastest? Slide 23 / 120 Slide 24 / 120 16 The first recorded world record is 10.8 seconds set 17 At what average speed did Asafa Powell run the by Luther Cary (USA 1891). How much time has 100 m in 2007? Show your work. been taken off the world record since it was first set in 1891?
Slide 25 / 120 Slide 26 / 120 18 Usain Bolt broke the world record on May 31, 2008. 19 Can you use the table to calculate instantaneous He then broke his own world record about two speeds? How about velocities? Explain why or months later. What was his average speed on each why not. day? Show your work for both days. Slide 27 / 120 Slide 28 / 120 20 How much faster (in terms of average speed) did 21 If an athlete were to run the 100 m dash at a speed Leroy Burrell run on June 14, 1991 to break the of 10.5 m/s, would they beat Usain Bolt's current record set by Carl Lewis on September 24, 1988? world record? Justify your answer. Show your work. Slide 29 / 120 Slide 30 / 120 22 What was Justin Gatlin's average speed on the day 23 Calculate the speed achieved by Maurice Green in that he broke the world record? Show your work. 1999. At this average speed, how long would it take Maurice to run 315 meters? Show your work.
Slide 31 / 120 Slide 32 / 120 24 What is the difference between average speed and instantaneous speed? Homework #2: Speed and Velocity Slide 33 / 120 Slide 34 / 120 25 Can average speed ever be equal to instantaneous 26 What is the average speed of a dog that runs 100 speed? Explain. m in 30 s? Show your work. Slide 35 / 120 Slide 36 / 120 27 Describe two examples of average speed and two 28 The Admiral train is traveling east at 100 mph and examples of instantaneous speed. the Alamo train is traveling west at 100 mph. Do they have the same speed? Do they have the same velocity? Explain why or why not.
Slide 37 / 120 Slide 38 / 120 29 Train A leaves New York for California at the same time Train B leaves California for New York. They are 2900 miles apart. They both travel at an average speed of 120 mph. Homework #3: Graphing Motion A What is the velocity of train A? B What is the velocity of train B? C How long will it take before they meet? Show your work. Slide 39 / 120 Slide 40 / 120 30 It is Field Day at your school and everyone is Name 10m 20m 30m 40m 50m 60m 70m 80m 90m ready for the potato sack race. Each grade has Susie 4s 9s 11s 15s 21s 23s 28s 32s 37s (6 th ) selected one person to enter the race. There are Joe (7 th ) 5s 15s 19s 24s 29s 33s 36s 41s 46s nine checkpoints along the racecourse. The table Thomas 6s 8s 11s 15s 20s 24s 28s 31s 35s (8 th ) below shows how long it took each student to get to each checkpoint. Graph the motion of the three contestants using a separate color/line pattern for each contestant. Be sure to plot position on the y- axis and time on the x-axis and label each axis. Slide 41 / 120 Slide 42 / 120 31 Who won the race? Explain how you can tell 32 Who had the fastest speed from 0- 30m? Justify from the graph. your answer with speed calculations for each student.
Slide 43 / 120 Slide 44 / 120 33 Who had the fastest speed from 0-60m? Justify your answer with speed calculation for each student. Classwork #3: Acceleration Slide 45 / 120 Slide 46 / 120 34 Define acceleration. 35 Write the formula for measuring the acceleration of an object. Be sure to explain what each part of the equation is. Slide 47 / 120 Slide 48 / 120 36 What is the SI unit of measurement for 37 Explain 3 different ways that an object can acceleration? accelerate.
Slide 49 / 120 Slide 50 / 120 38 What is the acceleration of a car that starts at rest 39 What is the acceleration of an object that starts at and increases its speed to 10 m/s in 2 seconds? 10 m/s and slows to 2 m/s in 4 seconds? Show Show your work. your work. Slide 51 / 120 Slide 52 / 120 40 Describe the speed and velocity of an object 41 Describe the speed and velocity of an object whose motion is shown in the speed vs time whose motion is shown in the position vs time graph below: graph below. What happens to the distance covered during each 5 second time interval? Slide 53 / 120 Slide 54 / 120 42 A student runs at constant speed on a circular racetrack. Does the student accelerate? Justify your answer. Homework #4: Acceleration
Slide 55 / 120 Slide 56 / 120 43 A car increases its speed. Is this acceleration 44 What is the acceleration of a rocket that is positive or negative? Explain. traveling at 20 m/s and increases its velocity to 40 m/s in 4 seconds? Show your work. Slide 57 / 120 Slide 58 / 120 45 What is the acceleration of a dragster that deploys 46 Describe the speed of an object whose motion is a parachute when travelling at 33 m/s and slows shown in the speed vs time graph below: to rest in 11 seconds? Show your work. Slide 59 / 120 Slide 60 / 120 47 Describe the speed of an object whose motion is shown in the position vs time graph below. What happens to the distance covered during each 5 second time interval? Classwork #4: Forces and Friction
Slide 61 / 120 Slide 62 / 120 48 Define a force. 49 What do forces do to objects? Describe an example. Slide 63 / 120 Slide 64 / 120 50 What is the “BIG IDEA” about the relationship 51 What is the unit for measuring force in the SI between forces and acceleration? system of measurement? Slide 65 / 120 Slide 66 / 120 52 Determine the net force in the diagram seen 53 Define friction and explain its effect on motion. below. Show how you came up with your answer.
Slide 67 / 120 Slide 68 / 120 54 What is static friction? Homework #5: Forces and Friction Slide 69 / 120 Slide 70 / 120 55 A force is a push or a pull acting on an object. 56 What happens to the motion of any object that How do forces affect motion when the forces are feels an unbalanced force? a) balanced? b) unbalanced? Slide 71 / 120 Slide 72 / 120 57 What types of friction occur when you ride a bike through a puddle? Justify your answer. Classwork #5: Gravity and Equilibrium
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