Concept explainers
Tidal energy Tides are now used so gene-ate electric power in two ways. In the first, huge dams can be built. across the mouth of a river where it exits to the ocean. As the ocean tide moves in and out of this tidal bas in or estuary, the water flows through tunnels in the dam (see Figure 9.19). This flowing water turns turbines in the tunnels that run electric generators. Unfortunately, this technique works best with large increases in tides—a 5-m difference between high and low tide Such differences are found at only a small number of places Currently, France is the only country that successfully uses this power source A tidal basin plant in France, the Rance. Tidal Power Station. makes 240 megawatts of power—enough energy to power 240,000 homes. Damming tidal basins can have negative environmental effects because of reduced tidal flow and silt buildup. Another disadvantage is that they can only generate electricity when the tide is flowing in or out, for about 10 hours each day.
A second method for collecting energy from the tidal flow (as well as all water flow) is to place turbines directly in the water—like windmills in moving water instead of in moving air. These water turbines have the advantages that they are much cheaper to build, they do not have the environmental problems of a tidal basin, and there are many more suitable sites for such water flow energy farms. Also the energy density of flowing water is about 800 times the energy density of dry air flow. Verdant Power is developing turbine prototypes in the East River near New York City and in the Saint Lawrence Seaway in Canada, and they are looking at other sites in the Puget Sound and all over the world. The worldwide potential tor hydroelectric power is about
Why do water turbines seem more promising than tidal basins for producing electric energy?
a. Turbines are less expensive to build.
b. Turbines have less impact on the environment.
c. There are many more locations for turbines than for tidal basins.
d. Turbines can operate 24 hours/day versus only 10 hours/day for tidal basins.
e. All of the above
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
COLLEGE PHYSICS:VOL.1
Additional Science Textbook Solutions
Life in the Universe (4th Edition)
Tutorials in Introductory Physics
Physics: Principles with Applications
University Physics with Modern Physics (14th Edition)
Introduction to Electrodynamics
Applied Physics (11th Edition)
- Review Return to Chapter 8 and the potential energy associated with both gravity near the surface of the Earth and universal gravity. a. What does the term reference configuration mean in the context of gravity? b. Suppose a system consists of an apple and the Earth, with the reference configuration set so that the systems gravitational potential energy is zero when the apple is on your desk. If the apple is above the desk, is the potential energy positive, negative, or zero? c. What is the conventional reference configuration for universal gravity? Why is that a convenient reference configuration? If a system consists of an apple and the Earth, does the systems gravitational potential energy increase, decrease, or stay the same as you raise the apple upward?arrow_forwardConsider the energy transfers and transformations listed below in parts (a) through (e). For each part, (i) describe human-made devices designed to pro-duce each of the energy transfers or transformations and, (ii) whenever possible, describe a natural process in which the energy transfer or transformation occurs. Give details to defend your choices, such as identifying the system and identifying other output energy if the device or natural process has limited efficiency. (a) Chemical potential energy transforms into internal energy. (b) Energy transferred by electrical transmission becomes gravitational potential energy. (c) Elastic potential energy transfers out of a system by heat. (d) Energy transferred by mechanical waves does work on a system. (e) Energy carried by electromagnetic waves becomes kinetic energy in a system.arrow_forwardA thin disk of mass M and radius R lies in the (x, y) plane with the z-axis passing through the center of the disk. Calculate the gravitational potential (z) and the gravitational field on the z-axis.arrow_forward
- Find the speed needed to escape from the solar system starting from the surface of Earth. Assume there are no other bodies involved and do not account for the fact that Earth is moving in its orbit. [Hint: Equation 13.6 does not apply. Use Equation 13.5 and include the potential energy of both Earth and the Sun. Substituting the values for Earth’s mass and radius directly into Equation 13.6, we obtain vesc=2GMR=2(6.67 10 11Nm2/kg2)(5.96 10 24kg)(6.37 106m)=1.12104m/s That is about 11 km/s or 25,000 mph. To escape the Sun, starting from Earth’s orbit, we use R=RES=1.501011m and MSum=1.991030kg . The result is vesc=4.21104m/s or about 42 km/s. We have 12mvesc2GMmR=12m02GMm=0 Solving for the escape velocity,arrow_forwardIn a hydroelectric dam, water falls 32.0 m and then spins a turbine to generate electricity. a.What is DeltaU of 1.0 kg of water? b.Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 49.0 MW of electricity? This is a typical value for a small hydroelectric damarrow_forwardA horizontal carousel is rotating around its axis with constant angular velocity w. On the carousel there is a straight track passing through its middle. A cart of mass m is traveling along the track with constant velocity v relative to the carousel. Note that there is friction between the cart and the carousel. FR XRarrow_forward
- Per: 1. A child is pulling a wagon with toys of varying masses in it. The combined mass of the wagon and the toys is initially 10 kg. The initial velocity is 0.89 m/s. Read each of the sentences that describe a change to the wagon and/or toys. For each scenario, circle whether the kinetic energy increases, decreases, or stays the same. A. The child increases the velocity of the wagon to 0.92 m/s. KE increases KE decreases KE remains the same B. The child removes a toy bear of mass 0.23 kg and the velocity remains the same. KE increases KE decreases KE remains the same C. The velocity of the wagon decreases to 0.27 m/s. KE increases KE decreases KE remains the same D. The child turns the wagon around, and its new velocity is -1.12 m/s. KE increases KE decreases KE remains the same E. The child adds 2.1 kg of rocks to the wagon and the velocity decreases to 0.71 m/s. KE increases KE decreases KE remains the same F. The child adds toys until the total mass is 11.6 kg, and the velocity…arrow_forwardIn a dam, water is flowing at the rate of 1400 kg/s and falls 40 m. The power is generated by the falling water is a. 548.8 MW b. 56 kW c. 548.8 kW d. 13.7 kWarrow_forward2. For a satellite in a circular orbit around the earth, the gravitational force from the earth on the satellite causes the centripetal acceleration. The amount of work done by the gravitational force from the earth on the satelliteA) is zeroB) is greater than zero.C) is less than zero.D) would be different if the masses of the earth and satellite were different.E) can’t be determined without a calculator and some data.i. Prove your answer by using the formula for work, W: (Hint: Consider just a short segment of the orbit, rather than the full revolution.) ii. Prove your answer by talking about the satellite’s kinetic energy, ∆?� ***also please do it i,ii and write a process detail.arrow_forward
- Let's say the Earth moves around the Sun in a circular orbit with a constant speed (neither is completely true, but they're very close, so let's just say it's true). Select the most correct statement about the work done on the Earth. A. The work done on the Earth is negative, since it is technically "falling" into the Sun, so its energy is decreasing. B. The work done on the Earth is zero, since the force of gravity is always perpendicular to the Earth'sdirection of motion.C. The work done on the Earth is zero, since the centripetal force cancels out the Sun's force of gravity.D. The work done on the Earth is positive, since it is technically "falling" into the Sun, its potential energy is decreasing, meaning its kinetic energy is increasing.E. The work done on the Earth is positive, since there is a net force on the Earth (the Sun's force of gravity) which is constantly changing the direction of the Earth's velocity.arrow_forwardA satellite is held in orbit by a 2 000-N gravitational force. Each time the satellite completes an orbit of circumference 80 000 km, the work done on it by gravity is a. 1.6 x108 J. b. 1.6 x 1011 J c. 6.4 x1011 J d. 0arrow_forward28. Jack & Jill went up the hill to fetch a pail of water. At the well, Jill used a force of 20.0 N to turn the crank handle of radius 0.400 m to rotate the axle of radius 0.100 m, so she could raise the 60.0 N bucket of water. What is the efficiency of the wheel? a. 50% b.75% c.100% d.150%arrow_forward
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice University
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics 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 Learning