What is limiting the more widespread use of hydrogen as a transportation fuel?

Photons with a wavelength of 599 nm in air enter a plate of flint glass with index of refraction n = 1.66. Find the speed, wavelength, and energy of a photon in the glass. (a) speed (in m/s) m/s (b) wavelength (in m) m (c) energy (in J)

A hot air balloon has a total mass of 750 kg (not including the air in the balloon) and holds a volume of 2.8 x 10^6 L of air. Assume the density of the air outside the balloon to be 1.2 kg/m^3 at a temperature of 20 degrees C and the air pressure is 101.3 kPa inside and outside the balloon. What is the minimum temperature for the air in the balloon to allow for the balloon to float? You can assume the air in the balloon to be an ideal gas and you must consider the mass of the air in the balloon as part of the total mass. Also, assume the molar mass of air to be 29 g/mol. (The answer is 379 K. Please show work.)

In a rectangular coordinate system, a positive point charge 5.0nC is placed at x=2cm, y=0cm and a negative point charge -5.0nC is placed at x=-2cm,y=0cm. Point P is at x=2cm, y=3cm

K=8.99 x 10^9 (Nxm^2)/C^2

a) Calculate the magnitude of the force between the positive charge and negative charge

b) Draw the electric field vector at point P, caused by the positive charge. Find its magnitude

c) Draw the electric field vector at point P, caused by the negative charge. Find its magnitude

d) Determine the magnitude and direction of the net electric field vector at point P

e) If a charge q=-4.0nC with a mass 2.0 x 10^-6 kg is released from rest at point P, what is its acceleration?

f) Calculate the electric potential at point P

For an angled launch how would your analysis of the ball's motion have to change if it fell to a height below it was launched. Clearly identify where and how the analysis changes. Formula used before was Range=Vicos(2(Visin)/g)

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.  
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