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
Physical Science (12th Edition), Standalone Book
- Find the current in 5.00 and 7.00 Ω resistors. Please explain all reasoningarrow_forwardFind the amplitude, wavelength, period, and the speed of the wave.arrow_forwardA long solenoid of length 6.70 × 10-2 m and cross-sectional area 5.0 × 10-5 m² contains 6500 turns per meter of length. Determine the emf induced in the solenoid when the current in the solenoid changes from 0 to 1.5 A during the time interval from 0 to 0.20 s. Number Unitsarrow_forward
- A coat hanger of mass m = 0.255 kg oscillates on a peg as a physical pendulum as shown in the figure below. The distance from the pivot to the center of mass of the coat hanger is d = 18.0 cm and the period of the motion is T = 1.37 s. Find the moment of inertia of the coat hanger about the pivot.arrow_forwardReview Conceptual Example 3 and the drawing as an aid in solving this problem. A conducting rod slides down between two frictionless vertical copper tracks at a constant speed of 3.9 m/s perpendicular to a 0.49-T magnetic field. The resistance of th rod and tracks is negligible. The rod maintains electrical contact with the tracks at all times and has a length of 1.4 m. A 1.1-Q resistor is attached between the tops of the tracks. (a) What is the mass of the rod? (b) Find the change in the gravitational potentia energy that occurs in a time of 0.26 s. (c) Find the electrical energy dissipated in the resistor in 0.26 s.arrow_forwardA camera lens used for taking close-up photographs has a focal length of 21.5 mm. The farthest it can be placed from the film is 34.0 mm. (a) What is the closest object (in mm) that can be photographed? 58.5 mm (b) What is the magnification of this closest object? 0.581 × ×arrow_forward
- Given two particles with Q = 4.40-µC charges as shown in the figure below and a particle with charge q = 1.40 ✕ 10−18 C at the origin. (Note: Assume a reference level of potential V = 0 at r = ∞.) Three positively charged particles lie along the x-axis of the x y coordinate plane.Charge q is at the origin.Charge Q is at (0.800 m, 0).Another charge Q is at (−0.800 m, 0).(a)What is the net force (in N) exerted by the two 4.40-µC charges on the charge q? (Enter the magnitude.) N(b)What is the electric field (in N/C) at the origin due to the two 4.40-µC particles? (Enter the magnitude.) N/C(c)What is the electrical potential (in kV) at the origin due to the two 4.40-µC particles? kV(d)What If? What would be the change in electric potential energy (in J) of the system if the charge q were moved a distance d = 0.400 m closer to either of the 4.40-µC particles?arrow_forward(a) Where does an object need to be placed relative to a microscope in cm from the objective lens for its 0.500 cm focal length objective to produce a magnification of -25? (Give your answer to at least three decimal places.) 0.42 × cm (b) Where should the 5.00 cm focal length eyepiece be placed in cm behind the objective lens to produce a further fourfold (4.00) magnification? 15 × cmarrow_forwardIn a LASIK vision correction, the power of a patient's eye is increased by 3.10 D. Assuming this produces normal close vision, what was the patient's near point in m before the procedure? (The power for normal close vision is 54.0 D, and the lens-to-retina distance is 2.00 cm.) 0.98 x marrow_forward
- Don't use ai to answer I will report you answerarrow_forwardA shopper standing 2.00 m from a convex security mirror sees his image with a magnification of 0.200. (Explicitly show on paper how you follow the steps in the Problem-Solving Strategy for mirrors found on page 1020. Your instructor may ask you to turn in this work.) (a) Where is his image (in m)? (Use the correct sign.) -0.4 m in front of the mirror ▾ (b) What is the focal length (in m) of the mirror? -0.5 m (c) What is its radius of curvature (in m)? -1.0 marrow_forwardAn amoeba is 0.309 cm away from the 0.304 cm focal length objective lens of a microscope.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





