Concept explainers
In a drag race, the position of a car as a function of time is given by x = bt2, with b = 2.000 m/s2. In an attempt to determine the car’s velocity midway down a 400-m track, two observers stand at the 180-m and 220-m marks and note when the car passes, (a) What value do the two observers compute for the car’s velocity over this 40-m stretch? Give your answer to four significant figures. (b) By what percentage does this observed value differ from the instantaneous value at x = 200 m?
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
Modified Mastering Physics With Pearson Etext -- Standalone Access Card -- For Essential University Physics (3rd Edition)
Additional Science Textbook Solutions
The Cosmic Perspective
University Physics Volume 2
Sears And Zemansky's University Physics With Modern Physics
Essential University Physics: Volume 2 (3rd Edition)
The Cosmic Perspective (8th Edition)
Tutorials in Introductory Physics
- A rocket ship has a position given by x(t)=bt2 meters. In order for it to reach a velocity of 5,000 m/s in 40,000 meters, what must be the value of b?arrow_forwardTwo runners start simultaneously from the same point on a circular 200-m track and run in opposite directions. One runs at a constant speed of 6.20 m/s, and the other runs at a constant speed of 5.50 m/s. When they first meet, (a) for how long a time will they have been running, and (b) how far will each one have run along the track?arrow_forwardOn a two-lane road, car A is travelling with a speed of 72 km/h. Two cars B and C approach car A in opposite directions with a speed of 108 km/h each. At a certain instant, when the distance AB is equal to AC, both being 2 km, B decides to overtake A before C does. What minimum acceleration of car B is required to avoid an accident ?arrow_forward
- The sport with the fastest moving ball is jai alai, where measured speeds have reached 303 km/h. If a professional jai alai player faces a ball at that speed and involuntarily blinks, he blacks out the scene for 100 ms. How far does the ball move during the blackout?arrow_forwardMost important in an investigation of an airplane crash by the U.S. National Transportation Safety Board is the data stored on the airplane’s flight-data recorder, commonly called the “black box” in spite of its orange coloring and reflective tape.The recorder is engineered to withstand a crash with an average deceleration of magnitude 3450 g during a time interval of 6.49 ms. In such a crash, if the recorder and airplane have zero speed at the end of that time interval, what is their speed at the beginning of the interval?arrow_forwardTraveling with an initial speed of 70 kph, a car accelerates at 6000 km/hr2 along a straight road. How long will ittake to reach a speed of 120 kph? Also, through what distance does the car travel during this time?arrow_forward
- An unidentified flying object (UFO) is observed to travel a total distance of 19000 m, starting and ending at rest, over a duration of 4.23 s. Assuming the UFO accelerated at a constant rate to the midpoint of its journey and then decelerated at a constant rate the rest of the way, what was the magnitude of its acceleration? Express your answer in g s , where 1 g = 9.81 m/s^2.arrow_forwardA classic physics problem states that if a projectile is shot vertically up into the air with an initial velocity of 146 feet per second from an initial height of 89 feet off the ground, then the height of the projectile, h, in feet, t seconds after it's shot is given by the equation: h=−16t2+146t+89h=-16t2+146t+89 Find the two points in time when the object is 126 feet above the ground (to one decimal places). Answer: The object is 126 feet off the ground at the following times: (Enter your two answers separated by a comma. Round to ONE decimal places.)arrow_forwardA daredevil jumps off a tall building. He falls freely for several secondsbefore releasing his parachute. His height (h) in meters, ? seconds afterjumping can be modeled by h = −4.9?2 + ? + 360 before he releases hisparachute and h = −4? + 142 after he released his parachute. How longafter jump did he release his parachute?arrow_forward
- After a ball rolls off the edge of a horizontal table at time t = 0, its velocity as a function of time is given by:v = 1.2 i - 9.8t jwhere v is in meters per second and t is in seconds. The ball’s displacement away from the edge of the table, during the time interval of 0.380 s for which the ball is in flight, is given by:Δ⃗r=∫00.380s⃗vdtTo perform the integral, you can use the calculus theorem:∫[A+Bf(x)]dx=∫Adx+B∫f(x)dx You can think of the units and unit vectors as constants, represented by A and B. Perform the integration to calculate the displacement of the ball from the edge of the table at 0.380 sarrow_forwardThe following table gives the position s1t2 of an object moving along a line at time t. Determine the average velocities over the time intervals 31, 1.014, 31, 1.0014, and 31, 1.00014. Then make a conjecture about the value of the instantaneous velocity at t = 1.arrow_forwardYou are exploring a planet and drop a small rock from the edge of a cliff. In coordinates where the +y direction is downward and neglecting air resistance, the vertical displacement of an object released from rest is given by y − y0 = 1/2gplanett2, where gplanet is the acceleration due to gravity on the planet. You measure t in seconds for several values of y − y0 in meters and plot your data with t2 on the vertical axis and y − y0 on the horizontal axis. Your data is fit closely by a straight line that has slope 0.300 s2/m. Based on your data, what is the value of gplanet?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