Textbook Question
Estimate the average speed with which the hair on your head grows. Give your answer in both m/s and μm/hour. Briefly describe how you arrived at this estimate.
31
views
Ch 01: Concepts of Motion
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch 01: Concepts of Motion35
- Ch 02: Kinematics in One Dimension75
- Ch 03: Vectors and Coordinate Systems58
- Ch 04: Kinematics in Two Dimensions60
- Ch 05: Force and Motion23
- Ch 06: Dynamics I: Motion Along a Line53
- Ch 07: Newton's Third Law27
- Ch 08: Dynamics II: Motion in a Plane52
- Ch 09: Work and Kinetic Energy56
- Ch 10: Interactions and Potential Energy50
- Ch 11: Impulse and Momentum56
- Ch 12: Rotation of a Rigid Body71
- Ch 13: Newton's Theory of Gravity52
- Ch 14: Fluids and Elasticity44
- Ch 15: Oscillations55
- Ch 16: Traveling Waves37
- Ch 17: Superposition39
- Ch 18: A Macroscopic Description of Matter53
- Ch 19: Work, Heat, and the First Law of Thermodynamics60
- Ch 20: The Micro/Macro Connection53
- Ch 21: Heat Engines and Refrigerators34
- Ch 22: Electric Charges and Forces40
- Ch 23: The Electric Field39
- Ch 24: Gauss' Law32
- Ch 25: The Electric Potential63
- Ch 26: Potential and Field57
- Ch 27: Current and Resistance42
- Ch 28: Fundamentals of Circuits39
- Ch 29: The Magnetic Field47
- Ch 30: Electromagnetic Induction60
- Ch 31: Electromagnetic Fields and Waves32
- Ch 32: AC Circuits63
- Ch 33: Wave Optics32
- Ch 34: Ray Optics57
- Ch 35: Optical Instruments30
- Ch 36: Special Relativity38
- Ch 37: The Foundations of Modern Physics25
- Ch 38: Quantization49
- Ch 39: Wave Functions and Uncertainty31
- Ch 40: One-Dimensional Quantum Mechanics35
- Ch 41: Atomic Physics18
- Ch 42: Nuclear Physics27
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 1, Problem 37
For Problems 34, 35, 36, 37, 38, 39, 40, 41, 42, and 43, draw a complete pictorial representation. Do not solve these problems or do any mathematics. A car starts from rest at a stop sign. It accelerates at 4.0 m/s² for 6.0 s, coasts for 2.0 s, and then slows at a rate of 2.5 m/s² for the next stop sign. How far apart are the stop signs?
Verified step by step guidance1
Step 1: Begin by creating a pictorial representation of the problem. Draw a horizontal line to represent the car's motion along the road. Mark the initial stop sign as the starting point (Position A) and the final stop sign as the ending point (Position B).
Step 2: Divide the motion into three distinct segments: (1) acceleration phase, (2) coasting phase, and (3) deceleration phase. Label these segments clearly on the diagram.
Step 3: For the acceleration phase, indicate that the car starts from rest (initial velocity = 0 m/s) and accelerates at 4.0 m/s² for 6.0 seconds. Use arrows to show increasing velocity during this phase.
Step 4: For the coasting phase, show that the car maintains a constant velocity (no acceleration) for 2.0 seconds. Represent this with a straight horizontal arrow of constant length.
Step 5: For the deceleration phase, indicate that the car slows down at a rate of 2.5 m/s² until it comes to rest at the next stop sign. Use arrows to show decreasing velocity during this phase, ending at Position B.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Kinematics
Kinematics is the branch of mechanics that deals with the motion of objects without considering the forces that cause the motion. It involves concepts such as displacement, velocity, acceleration, and time. Understanding kinematics is essential for analyzing the motion of the car in the problem, as it describes how the car's position changes over time.
Recommended video:
Guided course
08:25
Kinematics Equations
Acceleration
Acceleration is the rate of change of velocity of an object with respect to time. It can be positive (speeding up) or negative (slowing down), and is measured in meters per second squared (m/s²). In this problem, the car experiences different accelerations during its motion, which are crucial for determining how far it travels between the stop signs.
Recommended video:
Guided course
05:47Intro to Acceleration
Displacement
Displacement is a vector quantity that refers to the change in position of an object. It is defined as the shortest distance from the initial to the final position, along with the direction. In the context of the problem, calculating the total displacement of the car as it accelerates, coasts, and decelerates is necessary to find the distance between the stop signs.
Recommended video:
Guided course
06:13Displacement vs. Distance
Related Practice
Textbook Question
A jet plane is cruising at 300 m/s when suddenly the pilot turns the engines up to full throttle. After traveling 4.0 km, the jet is moving with a speed of 400 m/s. What is the jet's acceleration as it speeds up?
2
views
Textbook Question
A car traveling at 30 m/s runs out of gas while traveling up a 10° slope. How far up the hill will the car coast before starting to roll back down?
1
views
Textbook Question
Problems 44, 45, 46, 47, and 48 show a motion diagram. For each of these problems, write a one or two sentence 'story' about a real object that has this motion diagram. Your stories should talk about people or objects by name and say what they are doing.
8
views
Textbook Question
David is driving a steady 30 m/s when he passes Tina, who is sitting in her car at rest. Tina begins to accelerate at a steady 2.0 m/s² at the instant when David passes. How far does Tina drive before passing David?
1
views
Textbook Question
Compute the following numbers, applying the significant figure rules adopted in this textbook.
5
views