Please show work where applicable. Thanks! A. An object is moving in the positiv
ID: 1787311 • Letter: P
Question
Please show work where applicable. Thanks!
A. An object is moving in the positive x direction while a net force cted along the k-axisis exerted on the object. The figure at right rce as a function of position. What is the total work done o on the object over the distance shown? 3d a. Fod b. 3Fod/2 -F d. 4Fod B. A pendulum bob swings from point A to point 8 along the circular arc indicated at right. Which statement correctly describes the work done by gravity and by the tension force in the string? Gravity does zero work and the tension force does zero work b. Gravity does positive work and the tension force does negative work. c. Gravity does negative work and the tension force does zero work d. Gravity does positive work and the tension force does zero work. C. An object's speed decreases from 5 m/s to 4 m/s. The total work acting on the object was: a. b. c. d. Positive Negative Zero It depends on the direction of motion. D. It takes a work Wo to stretch a spring a distance x. How much work does it take to stretch the same spring a distance 2x? a. We/2 A crate of mass 20.0 kg slides across a rough surface with an initial velocity of 12.0 m/s and comes to rest over a distance of 8.00 m. E. a. b. c. d. What is the name of the force that brought the crate to rest? Did this force do positive, negative, or zero work? How much work did this force do? What was the magnitude of the force exerted on the crate?
Explanation / Answer
A). Work done = force × displacement × cos theta
Here in the graph area under the curve is the work doen but here we have to cosider the signs of the both according to the angle between force and displacement.
Net w = f.d + (1/2)f.d - (1/2).f.d = f.d
Hence option A is correct
B). Here in the pendulum
Gravity does positive work because angle between gravity and displacement of bob is less than 90 degree.
And tension force does zero work because angle between tension force and displacement is always 90 degree.
C). Here the acceleration is negative so force will be negative but work depends on the direction of displacement.
D).in spring force =k.x
If w is work done in stretching a spring x then 4w is the work done in stretching a spring 2x .
So w' = 4 .w hence option d is the answer.