Concept explainers
According to the definition of mechanical work, pushing on a rock accomplishes no work unless there is _
a. movement.
b. a net force.
c. an opposing force.
d. movement in the same direction as the direction of the force.
The correct option to complete the statement, “According to the definition of mechanical work, pushing on a rock accomplishes no work unless there is”, from the following options,
movement.
a net force.
an opposing force.
movement in the same direction as the direction of the force.
Answer to Problem 1AC
Solution:
Option (d) is correct.
Explanation of Solution
Introduction:
According to the concept of mechanical work, net work is done on an object if it experiences a net force that brings a displacement in the object.
Explanation:
Reason for the correct options:
When direction of applied force and direction of movement are same then only maximum work will be done.
Hence, option (d) is correct.
Reason for the incorrect options:
Option (a) is incorrect because the movement can be perpendicular to the direction of the force. Now if the angle between the force and the displacement is 90 degrees, then the work done comes out to be zero. Hence, it is a wrong option.
Option (b) is incorrect because the presence of net force does not give any information about the displacement of object which is necessary for any work to be done.
Option (c) is incorrect because even if an opposing force is present, there is no movement or there is a movement but at a right angle. So, opposing force doesn’t imply that work is always done. Hence, it is a wrong option.
Hence, options (a), (b) and (c) are incorrect.
Conclusion:
A force will do work on an object only if it has a component in the direction parallel to the motion of the object. Thus, a push on a rock will accomplish work only when the movement of the rock is in the same direction as the direction of the force.
Want to see more full solutions like this?
Chapter 3 Solutions
EBK PHYSICAL SCIENCE
- A fluid with density 263 kg/m3 flows through a pipe of varying diameter and height. At location 1 the flow speed is 13.5 m/s and the diameter of the pipe is 7.4 cm down to location 2 the pipe diameter is 16.9 cm. Location 1 is 6.3 meters higher than location 2. What is the difference in pressure P2 - P1? Using units in Pascals and use g = 9.81 m/s2.arrow_forwardThe kitchen had a temperature 46 degrees Fahrenheit and was converted it to Kelvin. What is the correct number for this temperature (46 F) on the Kelvin scale?arrow_forwardWater is traveling at a speed of 0.65 m/s through a pipe with a cross-section radius of 0.23 meters. The water enters a section of pipe that has a smaller radius, only 0.11 meters. What is the speed of the water traveling in this narrower section of pipe?arrow_forward
- A particular water pipe has a radius of 0.28 meters. If the pipe is completely filled with water, moving with average velocity 0.45 m/s, what is the flow rate of water through the pipe with units of cubic meters of water per second?arrow_forwardWater is flowing through a horizontal pipe with two segments. In one segment, the water flows at a speed v1 = 4.52 m/s. In the second segment the speed of the water is v2 = 2.38 m/s. Based on Bernoulli's Principle, what is the difference in pressure (P2 - P1) between the two segments? Assume that the density of the water is 997 kg/m3 and give your answer as the number of Pascals (i.e. N/m2).arrow_forwardWater from the faucet is supplied to the hose at a rate of 0.00057 m3/s. At what speed (number of meters per second) does the water exit the nozzle if the cross sectional area of the narrow nozzle is 2.1 x 10-6 m2?arrow_forward
- Jason Fruits/Indiana University Research Communications Silver/ silver oxide Zinc zinc/oxidearrow_forwardCar P moves to the west with constant speed v0 along a straight road. Car Q starts from rest at instant 1, and moves to the west with increasing speed. At instant 5, car Q has speed w0 relative to the road (w0 < v0). Instants 1-5 are separated by equal time intervals. At instant 3, cars P and Q are adjacent to one another (i.e., they have the same position). In the reference frame o f the road, at instant 3 i s the speed o f car Q greater than, less than, or equal to the speed of car P? Explain.arrow_forwardCar P moves to the west with constant speed v0 along a straight road. Car Q starts from rest at instant 1, and moves to the west with increasing speed. At instant 5, car Q has speed w0 relative to the road (w0 < v0). Instants 1-5 are separated by equal time intervals.arrow_forward
- Car P moves to the west with constant speed v0 along a straight road. Car Q starts from rest at instant 1, and moves to the west with increasing speed. At instant 5, car Q has speed w0 relative to the road (w0 < v0). Instants 1-5 are separated by equal time intervals. Sketch and label a vector diagram illustrating the Galilean transformation of velocities that relates velocity of car P relative to the road, velocity of car Q relative to road, and velocity of car Q relative to car P at instant 3. In the frame of car P, at instant 3 is car Q moving to the west, moving to the east, or at rest? Explain.arrow_forwardJust 5 and 6 don't mind 7arrow_forwardIn an electron gun, electrons are accelerated through a region with an electric field of magnitude 1.5 × 104 N/C for a distance of 2.5 cm. If the electrons start from rest, how fast are they moving after traversing the gun?arrow_forward
- University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillAn Introduction to Physical SciencePhysicsISBN:9781305079137Author:James Shipman, Jerry D. Wilson, Charles A. Higgins, Omar TorresPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning