Physics 105: Elementary Mechanics and Heat

SUNY Cortland

Fall 2023

Homework

Due	Reading	Problems	Posted
Due	Reading	Problems	Posted
Aug. 28			Aug. 28
Aug. 30	Chapter 1 sections 1.1, 1.2, and 1.4	Bring Math and Graphing Skills workbook to class	Aug. 28
Sept. 1		Find your way to my office during office hours, Sign-in and you are done. Not sure when they are? Check the syllabus. Have a time conflict? Check the syllabus.	Aug. 28
Sept. 4	Labor day	No class
Sept. 6	Chapter 2 cont. 2.1-2.3 Note that I have corrected the date (DNA-9/5/2023).		Aug. 28
Sept. 8	Chapter 2 cont. 2.4-2.6	Problem & Exercises (denoted as chapter.problem#): 1.1 (The speed limit...), 1.5 (Soccer fields...), Suppose a person has an average heart rate of 70 beats/min, how many beats will they have in 6 months? 1.29 (How many heartbeats...), 1.32 (Calculate the approximate...), 2.3 (Find the following for path C...), and 2.9 (On May 26, 1934...)	Sept 5
Sept. 11	Chapter 2 cont. 2.7-2.8		Sept 5
Sept. 13	Chapter 4: 1-3, practice P&E2.64		Sept 8
Sept. 15	Chapter 4: 4.4-4.6, practice P&E2.24		Sept. 8
Sept. 18	No new reading, practice P&E2.50	Chapter 2 Conceptual Questions: 2.16(If a subway...), 2.30(Consider the...). Problem and Exercises: 2.20(An olympic...) , 2.23(a light-rail...), 2.31, 2.34, 2.59, and 2.65 . Note new due date.	Sept. 12
Sept. 22	Chapter 3: 1-3, practice P&E4.3, P&E4.20		Sept 21
Sept. 25	Chapter 3 cont.:4, practice P&E 3.4, 3.18, 3.20		Sept 21
Sept. 27	Practice P&E 3.25, 3.40	Standing on the pedestrian path on the new Tappan Zee bridge (43m above the water) you throw a rock straight down toward the water (which may or may/not be legal) at 10m/s. Calculate and graph the velocity and position of the rock at 0.50s, 1.00s, 1.50s, and 2.00s. Be sure to clearly specify the coordinate system you are using (e.g., where you zero is, which direction is +). (a) Calculate the height of a cliff if it takes 2.35s for a rock to hit the ground after being thrown straight up at 3m/s. (b) How long would it take to reach the ground if thrown straight down at the same speed? A swimmer bounces straight up from a diving board and falls feet first into a pool. She leaves the diving board with a velocity of 4.00m/s up and at the same moment her feet are 1.80m above the water in the pool. (a) How long until she hits the water? (b) How high above the water do her feet get? (c) What is her velocity when she hits the water? A 63.0kg sprinter starts a race with an acceleration of 4.20m/s^2 (in the direction the runner is running). What is the net external force on the runner? Suppose two children (Alice and Burt) push horizontally on a third child (Charlie). Instead of working together Alice and Burt push in opposite directions, Alice with a force of 90.0N and Burt with a force of 75.0N. In addition to the forces from the two children the wheels of the wagon are rusty and provide a friction of 12.0N. The mass of Charlie, and the wagon he is sitting in is 23.0kg. In this problem we are interested in finding the acceleration that Charlie will experience as he continues to sit in the wagon. What is the object you will need to analyze the forces on? Draw a free-body diagram of that object. Calculate the acceleration. The next time these children play with the wagon it is rustier and the friction has risen to 15.0N, what is the acceleration now? Chapter 4 P&E 23 (A 5.00x10^5kg rocket...), Chapter 4 P&E 34 (...Superhero and Trusty the Sidekick...)	Sept 21
Sept. 29	Read 4.5 and 4.7		Sept. 21
Oct. 2	Read 4.5 and 4.7	Chapter 3 Problems and Exercises: Suppose you first walk 12.0m in a direction 25 degrees east of north and then 30.0m in a direction 35 degrees south of west. How far are you from your starting point? What is the compass direction of the line connecting your starting point to your ending point? Note that while you could do this analytically it is probably easier to do graphically. Suppose you first walk 12.0m due north and then 22.0m in a direction due west. How far are you from your starting point? What is the compass direction of the line connecting your starting point to your ending point? Please do this analytically. 3.40 Note that for the first question you must explain your process to get credit and for the last questions be sure to include a sketch, show your work, and explain your logic.	Sept. 28
Oct. 4	Review	Optional resources for preparing for the first exam--neither will be graded. The practice exam I distributed last year note that question 4 is not appropriate for your 1st exam and should be ignored the exam I gave last year.	Sept. 28
Oct. 6		Exam 1	Sept. 28
Oct. 9	Read 5.1-Static Friction		Sept. 28
Oct. 11	Read 5.1-Kinetic Friction	Problems and Exercises: 3.10 3.11 3.21a An archer shoots an arrow at a target 70.0m away. She looses the arrow at a height of 120cm from the ground, the same height as the bull's-eye of the target. (a) What angle should she shoot the arrow to hit the bull's-eye if the arrow is travelling at 35.0m/s? (b) A tree standing half-way between the archer and the target has a narrow branch sticking out 4.7m above the ground. Will the arrow go above, below, or hit the tree-branch? Note that for the first 3 question (3.10, 3.11) you must explain your process to get credit and for the last question be sure to include a sketch, show your work, and explain your logic.	Sept. 28
Oct. 13	5.2-Drag		Oct. 13
Oct. 16	Fall Break		Oct. 13
Oct. 18	Read 5.3-springs and restoring forces		Oct. 13
Oct. 20		4.42 (A 76.0kg person...), 5.4 (Suppose you have...), A baseball player with mass 79kg, sliding into second base, is retarded by a frictional force of magnitude 470N. What is the coefficient of kinetic friction between the player and the ground?, A 12N horizontal force pushes a block with mass 0.5kg against a vertical wall. The coefficient of static friction between the wall and the block is 0.60 and the coefficient of kinetic friction is 0.4. Assume that the block is not moving initially. Will the block move?, 5.17 ( consider the 52.0kg mountain...), 5.25 (calculate the velocity...), 5.31 (The lead in ...)	Oct. 13
Oct. 23	Chapter 6.1-6.3	First report due.	Oct. 13
Oct. 27	Chapter 6.5		Nov. 1
Nov. 1			Nov. 1
Nov. 3	7.4-7.5		Nov. 1
Nov. 6	7.6-7.9		Nov. 1
Nov. 8		A 50kg wooden crate is being pushed up a ramp with a force of 100N (parallel to the ramp) and is initially moving up the ramp at 5.0m/s. The coefficient of kinetic friction is 0.3 and the ramp slopes up at an angle of 20deg from level ground. Will the crate speed up, slow down, or move at a steady pace? Be sure your answer is well supported. A spring scale (e.g. this is a spring scale) stretches to be 3cm longer when 80g is placed on it. What is the spring constant of the spring in the scale? 6.4 (What is the period...), A baseball pitcher brings his arm forward during a ptich, rotation the forearm about the elbow. If the velocity of the ball in the pticher's hand is 43.0 m/s and the ball is 0.3m from the elbow joint, what is the angular velocity of the forearm? An ordinary workshop grindstone has a diameter of 15 cm. and rotates at 6500 rev/min. Calculate the centripital acceleration at its edge in m/s^2. What is the linear speed of a point at its edge? A 68kg student rides on a steadily rotating ferris wheel. At the highest point the normal force from the seat has a magnitude of 550N. Does the student feel light or heavy there? What is the magnitude of the normal force at the bottom of the ride? what is the magnitude of F_N at the top of the ride if the wheel's speed is doubled? In class we calculated the force on an 80kg person at an altitude of 340km above the surface of the earth and how fast the person is travelling. What if the person was orbiting in a circle at the same distance the moon is from the earth? Please find The force on an 80kg person orbiting the earth in a circular orbit 384,000km away from the earth The speed of the person as they orbit the earth in the same circular orbit as before. How does this compare to both the speed we found in class and the speed you found for question 6.4?	Nov. 1
Nov. 10	8.1-8.3		Nov. 6
Nov. 13	8.4, 9.1-9.3	7.12 (Calculate the force...), 7.21 (In a downhill ski race...), 7.22 (A 5.00x10^5kg subway...), 7.27 (Using energy considerations...), 7.32 (A person in good physical condition...), 7.56 (The swimmer shown in...), and A 75kg cross-country skier is climbing a 2.0deg slope at a constant speed of 3.00m/s and encounters air resistance of 25.0N. a) Find the rate of work done to him (power) by the gravitaional force and by the drag force. b) In light of this how much useful power must propel him forward (that is, disregard any issues related to the efficiency of the human body)? c) If he continues to push just as hard (same force) after the ground levels out how long will it take to reach 8m/s? (For this to be realistic he will need adjusts his stance to his drag force so low and be capable of expending this much higher power).	Nov. 6
Nov. 15	Review	Optional resources for preparing for the 2nd exam--neither will be graded. The practice exam I distributed last year the exam I gave last year.	Nov. 6
Nov. 17	Exam 2 (focused on Chapters 3-7)		Nov. 6
Nov. 20	9.1-9.3		Nov. 29
Nov. 22&24	Thanksgiving Break
Nov. 27	9.4-9.6		Nov. 29
Nov. 29	10.1-10.4, 11.1-11.4		Nov. 29
Dec. 1	11.5-11.7		Nov. 29
Dec. 4	12.1, 12.4-12.5, 12.7		Nov. 29
Dec. 6	13.1, 14.1, 14.2, 14.4		Nov. 29
Dec. 8		Test corrections due. Problems and Exercises: 8.27 (A 1.80kg falcon...), 9.9 (A person carries...), 9.15 (What minimum...), 9.33 (A 75kg man...), 10.8 (During a very quick...), ~~11.26 (A crass host...),~~ ~~12.64 (Oxygen reaches the...),~~ 14.3 (To sterilize a 50.0g...),	Nov. 29
Dec. 15		FinalExam 11-1pm .