For this problem, assume salt water and fresh water have the same density.

A large iceberg floats in the ocean. If the iceberg melts, the sea level will:

a) stay the same

b) fall

c) rise <---wrong answer!

Please also provide an explanation!

Explain why centrifugal force is a false (pseudo) force.

A skier traveling 14.0 m/s reaches the foot of a steady upward 20.0^o incline and glides 11.5 m up along this slope before coming to rest. Using mechanical energy methods what is the coefficient of friction?

1. Elmer Fudd pulls a 65.0 kg wooden crate of mass m across the floor with a force F at an angle of 34.0°. The coefficient of friction between the surfaces is m = 0.235. If the crate moves at a constant speed, what is the magnitude of the applied force F?

How does a newton cradle visually demonstrate how NRG and momentum are conserved. I konw it works mathematically but how does releasing balls and having the other two balls on the other side swing up demonstrate momentum and conservation of NRG.

6. One morning while waiting for class to begin, you are reading a newspaper article about airplane safety. This article emphasizes the role of metal fatigue in recent accidents. Metal fatigue results from the flexing of airframe parts in response to the forces on the plane especially during take off and landings. As an example, the reporter uses a plane with a take off weight of 200,000 lbs and take off speed of 200 mph which climbs at an angle of 30o with a constant acceleration to reach its cruising altitude of 30,000 feet with a speed of 500 mph. The three jet engines provide a forward thrust of 240,000 lbs by pushing air backwards. The article then goes on to explain that a plane can fly because the air exerts an upward force on the wings perpendicular to their surface called "lift." You know that air resistance is also a very important force on a plane and is in the direction opposite to the velocity of the plane. The article tells you this force is called the "drag." Although the reporter writes that some metal fatigue is primarily caused by the lift and some by the drag, she never tells you their size for her example plane. Luckily the article contains enough information to calculate them, so you do.

1. Focus (on) the Problem.

2. Describe the Physics

3. Plan a Solution

4. Execute Your Plan

5. Evaluate the Answer

(a) How many fringes appear between the first diffraction-envelope minima to either side of the central maximum in a double-slit pattern if λ = 699 nm, d = 0.200 mm, and a = 36.9 µm? (b) What is the ratio of the intensity of the third bright fringe to the intensity of the central fringe?

6.   A   10.0-kg   mass   is   traveling   to   the   right   with   a   speed   of   2.00   m/s   on   a   frictionless   horizontal   surface   when   it   collides   with   and   sticks   to   a   second   10.0-kg   mass   that   is   initially   at   rest   but   is   attached   to   a   light   spring   that   is   neither   stretched   nor   compressed   with   a   force   constant   80.0   N/m.   The   system   undergoes   SHM.   A)   Find   the   frequency,   amplitude,   the   period   of   the   subsequent   oscillations   and   the   phase   angle.   B)   Find   the   maximum   and   minimum   velocities   and   acceleration   attained   by   the   oscillating   system   C)   How   long   does   it   take   the   system   to   return   the   first   time   to   the   position   it   had   immediately   after   the   collision?   D)   Write   the   equations   for   the   displacement,   velocity,   and   acceleration   of   the   system   as   function   of   time.  

7.   In   March   2006,   two   small   satellites   were   discovered   orbiting   Pluto,   one   at   a   distance   of   48,000   km   and   the   other   at   64,000   km.   Pluto   already   was   known   to   have   a   large   satellite   Charon,   orbiting   at   19,600   km   with   an   orbital   period   of   6.39   days.   Assuming   that   the   satellites   do   not   affect   each   other,   find   the   orbital   periods   of   the   two   small   satellites   without   the   mass   of   Pluto.  
Figure

Your grandfather clock is a simple pendulum with a length of 0.994 m. If the clock loses 3 min in a week, how should you adjust the length of the pendulum so that it can properly keep time?

what's the safest way to use a meter while testing for voltage

In the figure, a uniform plank, with a length L of 5.23 m and a weight of 280 N, rests on the ground and against a frictionless roller at the top of a wall of height h = 1.59 m. The plank remains in equilibrium for any value of θ = 70.0° or more, but slips if θ < 70.0°. Find the coefficient of static friction between the plank and the ground.

Ch 29

44. In an atom, an electron has the following allowed energy levels, E1 = 1 eV, E2 = 4 eV and E3 = 6 eV. What are the observed emission and absorption wavelengths for this atom? Absorption: 414.4 nm, 248.6 nm, Emission: 414.4 nm, 248.6 nm, 621.6 nm

45. In LASIK surgery, a laser is used to reshape the cornea of the eye to improve vision. The laser produces extremely short pulses of light, each containing 1 mJ of energy. a) In each pulse there are 9.7 x 1014 photons. What is the wavelength of the laser? 192.9 nm b) Each pulse lasts only 20 nsec. What is the average power delivered to the eye during a pulse? 50kW

46. An electron with a speed of 4 x 106 m/s collides with an atom. The collision excites the atom from its ground state (1 eV) to a state with an energy of 8.9 eV. What is the speed of the electron after the collision? 3.64 x 106 m/s

48. The absorption spectrum for an atom consists of the wavelengths 200 nm, 300 nm and 500 nm.

a) Draw the energy level diagram for this atom, labeling the energy (in eV) for each level. The ground state energy level is at 0 eV. E2 = 2.49 eV. E3 = 4.14 eV, E4 = 6.22 eV

b) What wavelengths are seen in the emission spectrum? 753.4 nm, 333.3 nm, 597.7 nm

Back-of-the-envelope CO: It is well-known (certainly among astronomers) that the Einstein A-coefficient for the Lyman alpha (n = 2 to n = 1) transition in atomic hydrogen is of order 10^9 s^−1 (actually, 5 × 10^8 s^−1). As we briefly discussed in class, this result could be estimated to order-of-magnitude by considering an (accelerating) electron on a spring that displaces a Bohr radius, a0, and has natural angular frequency ω and then taking the inverse lifetime of the excited state as A ∼ P/ω, where P is the power radiated by an accelerating charge. The ubiquitous carbon monoxide molecule, 12CO, is used by astronomers to trace the presence and measure the temperature of molecular gas in various astrophysical environments. We would rather try to detect H2 directly, but sadly H2 has no permanent electric dipole moment because of its symmetry, while Carbon monoxide does have a permanent dipole moment, so is easier to detect.

a)Estimate the wavelength of the lowest energy, rotational transition in CO (J = 1 to J = 0, where J is the rotational quantum number). Do this by considering a barbell spinning about its axis of greatest moment of inertia and recognizing that angular momentum comes quantized in units of ?h. Compare your estimate
to the true answer of 2.6 mm.

b)Use scaling relations to estimate the Einstein A coefficient of this transition, i.e., the inverse lifetime of the excited J = 1 state. You can use that the dipole moment (that is difficult to guess from first principles) of the CO molecule is 0.1 Debyes, not ∼ 1 Debye, as one might have guessed naively (1 Debye= 10^−18cgs. Note that ea0 = 2.5 Debyes, where e is the electron charge). Compare your estimate to the true answer A10 = 7.4 × 10^-8 s^-1.

Note: This smaller-than-expected dipole moment of CO is a consequence of the strong double bond connecting C to O. Most other molecules common in astrophysics – e.g., H2O, CS, SiS, SiO, HCN, OCS, HC3N – have dipole moments that are all of order 1 Debye.