Concept explainers
A Supersonic Waterfall Geologists have learned of periods in the past when the Strait of Gibraltar closed off, and the Mediterranean Sea dried out and become a desert. Later, when the strait reopened, a massive saltwater waterfall was created. According to geologists, the water in this waterfall was supersonic; that is, it fell with speeds in excess of the speed of sound. Ignoring air resistance, what is the minimum height necessary to create a supersonic waterfall? (The speed of sound may be taken to be 340 m/s.)
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
Physics (5th Edition)
Additional Science Textbook Solutions
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
University Physics Volume 2
Sears And Zemansky's University Physics With Modern Physics
University Physics with Modern Physics (14th Edition)
College Physics (10th Edition)
- Two boats start together and race across a 60-km-wide lake and back. Boat A goes across at 60 km/h and returns at 60 km/h. Boat B goes across at 30 km/h, and its crew, realizing how far behind it is getting, returns at 90 km/h. Turnaround times are negligible, and the boat that completes the round trip first wins. (a) Which boat wins and by how much? (Or is it a tie?) (b) What is the average velocity of the winning boat?arrow_forwardA glider of length moves through a stationary photogate on an air track. A photogate (Fig. P2.44) is a device that measures the time interval td during which the glider blocks a beam of infrared light passing across the photogate. The ratio vd = /td is the average velocity of the glider over this part of its motion. Suppose the glider moves with constant acceleration. (a) Argue for or against the idea that vd is equal to the instantaneous velocity of the glider when it is halfway through the photogate in space. (b) Argue for or against the idea that vd is equal to the instantaneous velocity of the glider when it is halfway through the photogate in time.arrow_forwardTwo boats start together and race across a 60-km-wide lake and back. Boat A goes across at 60 km/h and returns at 60 km/h. Boat B goes across at 30 km/h, and its crew, realizing how far behind it is getting, returns at 90 km/h. Turnaround times are negligible, and the boat that completes the round trip first wins. (a) Which boat wins and by how much? (Or is it a tie?) (b) What is the average velocity of the winning boat?arrow_forward
- A certain automobile manufacturer claims that its deluxe sports car will accelerate from rest to a speed of 42.0 m/s in 8.00 s. (a) Determine the average acceleration of the car. (b) Assume that the car moves with constant acceleration. Find the distance the car travels in the first 8.00 s. (c) What is the speed of the car 10.0 s after it begins its motion if it can continue to move with the same acceleration?arrow_forwardA man drops a rock into a well, (a) The man hears the sound of the splash 2.40 s after he releases the rock from rest. The speed of sound in air (at the ambient temperature) is 336 m/s. How far below the top of the well is the surface of the water? (b) What If? II the travel time for the sound is ignored, what percentage error is introduced when the depth of the well is calculated?arrow_forwardAn elevator moves downward in a tall building at a constant speed of 5.00 m/s. Exactly 5.00 s after the top of the elevator car passes a bolt loosely attached to the wall of the elevator shaft, the bolt falls from rest, (a) At what time does the bolt hit the top of the still-descending elevator? (b) In what way is this problem similar to Example 2.8? (c) Estimate the highest floor from which the bolt can fall if the elevator reaches the ground floor before the boll hits the top of the elevator.arrow_forward
- Automotive engineers refer to the time rate of change of acceleration as the jerk. Assume an object moves in one dimension such that its jerk J is constant. (a) Determine expressions for its acceleration ax(t), velocity vx(t), and position x(t), given that its initial acceleration, velocity, and position are axi, vxi, and xi, respectively. (b) Show that ax2 = axi2 + 2J(vx vxi).arrow_forwardA glider of length moves through a stationary photogate on an air track. A photogate (Fig. P2.19) is a device that measures the time interval td during which the glider blocks a beam of infrared light passing across the photogate. The ratio vd = /td is the average velocity of the glider over this part of its motion. Suppose the glider moves with constant acceleration. (a) Argue for or against the idea that vd is equal to the instantaneous velocity of the glider when it is halfway through the photogate in space. (b) Argue for or against the idea that vd is equal to the instantaneous velocity of the glider when it is halfway through the photogate in time. Figure P2.19arrow_forward]=An inquisitive physics student and mountain climber climbs a 55.0-m-high cliff that overhangs a calm pool of water. He throws two stones vertically downward, 1.00 s apart, and observes that they cause a single splash. The first stone has an initial speed of 2.20 m/s. (a) How long after release of the first stone do the two stones hit the water? s (b) What initial velocity must the second stone have if the two stones are to hit the water simultaneously? magnitude m/s direction (c) What is the speed of each stone at the instant the two stones hit the water? first stone m/s second stone m/sarrow_forward
- A) physics student with too much free time drops a watermelon from a roof of a building. hears the sound of the watermelon going “splat” 2.5s later. How high is the building? The speed of sound is 340m/s. You may ignore air resistance. B) An athlete whose mass is 90.0 kg is performing weight-lifting exercises. Starting from the rest position, he lifts, with constant acceleration, a barbell that weighs 490 N. He lifts the barbell a distance of 0.60 m in 1.6 s. Find the total force that his feet exert on the ground as he lifts the barbell C) An ideal spring of negligible mass is 12.00 cm long when nothing is attached to it. When you hang a 3.15-kg weight from it, you measure its length to be 13.40 cm. If you wanted to store 10.0 J of potential energy in this spring, what would be its total length? Assume that is continues to obey Hooke’s lawarrow_forwardAn initially stationary hovercraft sits on a large lake. Whena whistle blows the hovercraft accelerates due north at a rate of1.2 m s−2for 10 s, does not accelerate at all for the next 10 s, andthen accelerates at a rate of 0.6 m s−2 due east for another 10 s. Thehovercraft then coasts for another 10 s without any acceleration.(a) What is the velocity of the hovercraft 40 s after the whistleblows?(b) What is the displacement of the hovercraft 40 s after thewhistle blows?arrow_forward
- Physics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegePhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning