Concept explainers
(a) A light-rail commuter train accelerates at a rate of 1.35 m/s2. How long does it take to reach its top speed of 80.0 km/h, starting from rest? (b) The same train ordinarily decelerates at a rate of 1.65 m/s2. How long does it take to come to a stop from its top speed? (c) In emergencies the train can decelerate more rapidly, coming to rest from 80.0 km/h in 8.30 s. What is its emergency deceleration in m/s2?
Trending nowThis is a popular solution!
Learn your wayIncludes step-by-step video
Chapter 2 Solutions
College Physics
Additional Science Textbook Solutions
Biology 2e
Essential University Physics: Volume 2 (3rd Edition)
College Physics: A Strategic Approach (3rd Edition)
University Physics Volume 1
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Tutorials in Introductory Physics
- a) A light-rail commuter train accelerates at a rate of 1.51 m/s². How long does it take to reach its top speed of 71.7 km/hr, starting from rest? b) The same train ordinarily decelerates at a rate of 1 m/s². How long does it take to come to a stop from its top speed? c) In emergencies the train can decelerate more rapidly, coming to rest from 71.7 km/hr in 6.59 s. What is its emergency deceleration?arrow_forwardA car sits on an entrance ramp to a freeway, waiting for a break in the traffic. Then the driver accelerates with constant acceleration along the ramp and onto the freeway. The car starts from rest, moves in a straight line, and has a speed of 20 m/s 145 mi/h2 when it reaches the end of the 120-m-long ramp. (a) What is the acceleration of the car? (b) How much time does it take the car to travel the length of the ramp? (c) The traffic on the freeway is moving at a constant speed of 20 m/s.What distance does the traffic travel while the car is moving the length of the ramp?arrow_forwardIn a collision, an automobile initially traveling at 50 km/h decelerates at a constant rate of 200 m/s2. A passenger not wearing a seatbelt crashes against the dashboard. Before the collision, the distance between the passenger and the dashboard was 0.60 m. With what speed relative to the automobile does the passenger crash into the dashboard? Assume that the passenger has no deceleration before contact with the dashboard.arrow_forward
- From rest, the cheetah can accelerate at 8.8 m/s2 and reach a top speed of 30 m/s (108 km/h)! It can maintain this maximum speed over a distance of about 400 meters before it needs to stop.On the other hand, the Thomson’s gazelle has a top speed of 70 km/h, which is less than the cheetah’s, but it can maintain this top speed for a while as well. From rest, the gazelle can accelerate at 4.5 m/s2 to reach its top speed. Q1. After what total distance from rest must the cheetah stop? (clearly show calculations) Q2. In the elapsed time that the cheetah started and must stop, what distance can the gazelle cover? (again clearly show your calculations)arrow_forwardFrom rest, the cheetah can accelerate at 8.8 m/s2 and reach a top speed of 30 m/s (108 km/h)! It can maintain this maximum speed over a distance of about 400 meters before it needs to stop.On the other hand, the Thomson’s gazelle has a top speed of 70 km/h, which is less than the cheetah’s, but it can maintain this top speed for a while as well. From rest, the gazelle can accelerate at 4.5 m/s2 to reach its top speed. When a cheetah goes after a gazelle, success or failure is a simple matter of kinematics: you will determine if the cheetah’s high speed is enough to allow it to reach its prey before it runs out of steam (or time).You will apply basic kinematics and simple assumptions to determine how a chase can play out. The Scene:A cheetah has spotted a gazelle. At the same instant the cheetah leaps into action, the gazelle has spotted him and starts heading directly away.Q1. After what total distance from rest must the cheetah stop? (clearly show calculations and substitutions) Q2.…arrow_forwardFrom rest, the cheetah can accelerate at 8.8 m/s2 and reach a top speed of 30 m/s (108 km/h)! It can maintain this maximum speed over a distance of about 400 meters before it needs to stop.On the other hand, the Thomson’s gazelle has a top speed of 70 km/h, which is less than the cheetah’s, but it can maintain this top speed for a while as well. From rest, the gazelle can accelerate at 4.5 m/s2 to reach its top speed. When a cheetah goes after a gazelle, success or failure is a simple matter of kinematics: you will determine if the cheetah’s high speed is enough to allow it to reach its prey before it runs out of steam (or time).You will apply basic kinematics and simple assumptions to determine how a chase can play out. Q2. In the elapsed time that the cheetah started and must stop, what distance can the gazelle cover? (again clearly show your calculations) Why is the 70 multiplied by 5/18?arrow_forward
- An electric vehicle starts from rest and accelerates at a rate of 2.0 m/s² in a straight line until it reaches a speed of 20 m/s. The vehicle then slows at a constant rate of 1.0 m/s? until it stops. (a) How much time elapses from start to stop? (b) How far does the vehicle travel from start to stop?arrow_forwardA light-rail commuter train accelerates at a rate of 1.45 m/s“. How long (in s) does it take to reach its top speed of 80.0 km/h, starting from rest? The same train ordinarily decelerates at a rate of 1.75 m/s2. How long (in s) does it take to come to a stop from its top speed? In emergencies the train can decelerate more rapidly, coming to rest from 80.0 km/h in 8.30 s. What is its emergency deceleration in m/s?? m/s2arrow_forwardA startled armadillo leaps upward, rising 0.586 m in the first 0.204 s. (a) What is its initial speed as it leaves the ground? (b) What is its speed at the height of 0.586 m? (c) How much higher does it go? Use g=9.81 m/s2.arrow_forward
- A car sits on an entrance ramp to a freeway, waiting for a break in the traffic. Then the driver accelerates with constant acceleration along the ramp and onto the freeway. The car starts from rest, moves in a straight line, and has a speed of 20 m/s (45 mi/h) when it reaches the end of the 120-m-long ramp. (a) What is the acceleration of the car? (b) How much time does it take the car to travel the length of the ramp? (c) The traffic on the freeway is moving at a constant speed of 20 m/s.What distance does the traffic travel while the car is moving the length of the ramp?arrow_forwardA certain cable car in San Francisco can stop in 10 s when traveling at maximum speed. On one occasion, the driver sees a dog a distance d in front of the car and slams on the brakes instantly. The car reaches the dog 7.40 s later, and the dog jumps off the track just in time. If the car travels 3.80 m beyond the position of the dog before coming to a stop, how far was the car from the dog? (Hint: You will need three equations.) marrow_forwardA subway train starts from rest at a station and accelerates at a rate of 2.50 m/s2 for 15.90 seconds. It then runs at a constant speed for 35 seconds and then slows down at a rate of 4.50 m/s2 until it stops at the next station. (a) What is the speed of the train just before it starts slowing down? (b) How long did it take the train to finish the trip from one station to the other?arrow_forward
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningUniversity Physics (14th Edition)PhysicsISBN:9780133969290Author:Hugh D. Young, Roger A. FreedmanPublisher:PEARSONIntroduction To Quantum MechanicsPhysicsISBN:9781107189638Author:Griffiths, David J., Schroeter, Darrell F.Publisher:Cambridge University Press
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningLecture- Tutorials for Introductory AstronomyPhysicsISBN:9780321820464Author:Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina BrissendenPublisher:Addison-WesleyCollege Physics: A Strategic Approach (4th Editio...PhysicsISBN:9780134609034Author:Randall D. Knight (Professor Emeritus), Brian Jones, Stuart FieldPublisher:PEARSON