« previous next »

Author Question: A puck moves on a horizontal air table. It is attached to a string that gradually winds itself up ... (Read 44 times)

Arii_bell

  • Hero Member
  • *****
  • Posts: 596
on: Jul 29, 2018
A puck moves on a horizontal air table. It is attached to a string that gradually winds itself up around a round peg in the center of the table. This shortens the string, so the puck gradually spirals in towards the center.
 
  What happens to the magnitude of the puck's angular momentum?

Question 2

What is the energy of a photon that, when it is absorbed by a hydrogen atom, excites an electron from the ground state of the hydrogen atom to the n = 2 state?
 
  A) 10.2 eV
  B) 1.63  10-18 J
  C) 1.63  10-18 Nm
  D) All of the answers are correct.
  E) None of the answers is correct.


nickk12214

  • Sr. Member
  • ****
  • Posts: 332
Reply #1 on: Jul 29, 2018
Answer to Question 1

The tension in the string is perpendicular to the path of the puck, so there is no work done on the puck, but there is a retarding torque on it about the center of the table because the string pulls in a direction tangent to the peg, not towards the peg's center. Thus, its energy is constant but the magnitude of its angular momentum decreases.

Answer to Question 2

D


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.

Did you know?

Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).

Did you know?

A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.

Did you know?

Drug-induced pharmacodynamic effects manifested in older adults include drug-induced renal toxicity, which can be a major factor when these adults are experiencing other kidney problems.

Did you know?

If you use artificial sweeteners, such as cyclamates, your eyes may be more sensitive to light. Other factors that will make your eyes more sensitive to light include use of antibiotics, oral contraceptives, hypertension medications, diuretics, and antidiabetic medications.

The Z scheme, which depicts the energy of an electron as it moves from photosystem II to NADP+ The Z scheme, which depicts the energy of an electron as it moves from photosystem II to NADP+
Water potentials decrease (become more negative) as one moves from soil to plant to atmosphere Water potentials decrease (become more negative) as one moves from soil to plant to atmosphere
Louis Comfort Tiffany, Tiffany Studios, Water-lily table lamp. Louis Comfort Tiffany, Tiffany Studios, Water-lily table lamp.
The Periodic Table of Elements. The Periodic Table of Elements.
Chrysler also recommends that a clear plastic hose (1/4" ID) be attached to the bleeder valve ... Chrysler also recommends that a clear plastic hose (1/4" ID) be attached to the bleeder valve ...
graphic(04-40.jpg) Mary pushes horizontally on a large, heavy table which is s graphic(04-40.jpg) Mary pushes horizontally on a large, heavy table which is s
Video: Oogenesis Animation

For a complete list of videos, visit our video library