Concept explainers
I was driving along at 20 m/s, trying to change a CD and not watching where I was going. When I looked up, I found myself 45 m from a railroad crossing. And wouldn’t you know it, a train moving at 30 m/s was only 60 m from the crossing. In a split second, I realized that the train was going to beat me to the crossing and that I didn’t have enough distance to stop. My only hope was to accelerate enough to cross the tracks before the train arrived. If my reaction time before starting to accelerate was 0.50 s, what minimum acceleration did my car need for me to be here today writing these words?
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
Modified Mastering Physics with Pearson eText -- Standalone Access Card -- for Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
- Jim is driving his car at 32m/s (72mi/h) along a highway where the speed limit is 25m/s (55mi/h). A highway patrol car observes him pass and quickly reaches a speed of 36m/s. At that point, Jim is 300m ahead of the patrol car. How far does the patrol car travel before catching Jim?arrow_forwardA driver is traveling 18.0 m/s when she sees a red light ahead. Her car is capable of decelerating at a rate of 3.65m / (s ^ 2) If it takes her 0.380 s to get the brakes on and she is 24.0 m from the intersection when she sees the light, will she be able to stop in time? How far from the beginning of the intersection will she be, and in which direction?arrow_forwardArchibald, an aging geezer, is out bicycling one fine afternoon, reliving his glorious youth and oblivious to the world around him. As he approaches a busy intersection, a police officer directing traffic blows his whistle to get Archie’s attention so he’ll slow down and stop. But Archie doesn’t stop; he just speeds right through the intersection as if the traffic cop wasn’t even there. The cop radios one of his colleagues and gets her to stop the old geezer. She gives him a traffic citation for failing to heed the command of a police officer directing traffic. When the case gets to traffic court, Archie explains to the judge that he didn’t hear the officer’s whistle because he is going deaf and cannot hear frequencies above 3000 Hz. The traffic cop informs the judge that his standard issue police whistle emits a frequency of 2100 Hz and he has a certificate to prove it. Thinking quickly (at least for an old geezer) Archie says that it may be true that the police whistle emits a sound…arrow_forward
- The first supersonic flight was performed by Charles Yeager in 1947. During his attempt, he flew from 119 m/s to top speed, accelerating at 7.29 m/s^2 for a distance of 5251 m. What top speed did he achieve?arrow_forwardWhen the legal speed limit for the New York Thruway was increased from 55 mi/h to 65 mi/h, how much time was saved by a motorist who drove the 700 km between the Buffalo entrance and the New York City exit at the legal speed limit?arrow_forwardA driver in Spain is on a street that has a posted speed limit of vm=75 km/hr and is traveling above the speed limit by vc=28 km/hr. A SUV pulls out of a garage into the street in front of the driver d=24 m in front if of the driver and stops there. The driver immediately brakes and begins decelerating at a rate of ab=4.9 m/s^2. How fast in meters per second is the driver traveling when he hits the SUV in front of him?arrow_forward
- You normally drive on a freeway between San Diego and Los Angeles at an average speed of 105 km/h, and the trip takes 2 h and 20 mins. On a Friday afternoon, however, heavy traffic slows you down and you drive the same distance at an average speed of only 70 km/h. How much longer does the trip take?arrow_forwardA car enters the freeway with a speed of 8 m/s and accelerates uniformly for 3.5 km in 2.5 min. How fast is the car moving after this time?arrow_forwardA shopper uses the 55-meter long walkalator that goes at 1.5 m/s from the meat section to the vegetable section of a supermarket. If the shopper walks at 1.25 m/s in the same direction as the walkalator, how long will it take her to reach the vegetable section?arrow_forward
- A car is coasting backwards down hill at a speed of 3.0m/s when the driver gets the engine started. After 2.5seconds, the car is moving up hill at 4.5m/s. assuming that uphill is positive direction, what is the car average acceleration?arrow_forwardA football player runs 40 meters to the right in 8 seconds. From this we know _ The acceleration is 5 m/s/s The final velocity is 5 m/s The initial velocity is 0 m/s The average velocity is 5 m/sarrow_forwardMohammed is driving his car at 80 km/hr speed from Alaya and Ahmed is driving his car at 60 km/hr from Thapti. If both start at the same time, with Ahmed 200 m ahead, the time in which Mohammed catches Ahmed will be a. 3.6036 s b. 360.36 s c. 36.036 s d. 18.018sarrow_forward
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice University
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning