Theories, Problems, Solutions

Photon Energies

Crazy Horse — Wed, 07 Sep 2005 23:13:55 -0400

Radiated Energy

Crazy Horse — Wed, 03 Aug 2005 07:00:00 -0400

If the absolute temperature of a blackbody is increased by a factor of three, the energy radiated per second, per unit area:

(1) decreases by a factor of 9

(2) increrases by a factor of 9

(3) increases by a factor of 27

(4) decreases by a factor of 81

(5) increases by a factor of 81

Destructive Interference

Crazy Horse — Sun, 31 Jul 2005 10:00:00 -0400

Two idenical speakers driven by the same signal produce 680 Hz soundwaves. The speakers are different distances away from you. What must be the difference in distances to result in destructive interference?

(1) 0.85 m

(2) 1.3 m

(3) .30 m

(4) .25 m

Blow my Horn

Crazy Horse — Thu, 21 Jul 2005 22:02:09 -0400

An engineer in a moving train blows the train's horn while the train is moving away from a woman standing on a nearby platform. Compared to the frequency of the sound that the engineer hears, the lady standing on the platform hears a sound with:

(1) the same wavelength

(2) more variation in tone

(3) greater amplitude

(4) a lower frequency

Force

Crazy Horse — Thu, 21 Jul 2005 00:46:07 -0400

A college soccer star runs towards the opposing goal and kicks a 0.5 kg stationary inflated ball with a total force of 50 newtons. What is the force on the athlete's foot?

(1) 0 N

(2) 25 N

(3) 50 N

(4) 100 N

Stored Energy

Crazy Horse — Sun, 17 Jul 2005 14:47:55 -0400

A 3 microfarad capacitor is connected with a 6 microfarad capacitor. When a 300 volt potential difference is applied across this combination, the total energy stored in the two capacitors is:

(1) 0.41 J

(2) 0.27 J

(3) 0.09 J

(4) 0.81 J

(5) 0.18 J

Acceleration

Crazy Horse — Sat, 02 Jul 2005 11:03:50 -0400

A net force of 10 newtons accelerates an object at 5.0 meters per second². What net force would be required to accelerate the same object at 1.0 meter per second²?

(1) 1N
(2) 2N
(3) 5N
(4) 50N

Friction

Crazy Horse — Thu, 30 Jun 2005 07:40:07 -0400

A snowboarder starting at rest comes down a slope at an angle of 30 degrees with the horizontal. The skier makes a total vertical descent of 100 m and then coasts along a level section which runs for 400m before entering the beginner's area.

(1) How large must the coefficient of friction be to just prevent the aggressive snowboarder from entering the learning area, and wreaking havoc?

(2) Using the coefficient of friction found in (1) what is the maximum velocity that can be attained by the snowboarder?

Playing with Water

Crazy Horse — Fri, 17 Jun 2005 11:36:11 -0400

Which quantity is equivalent to the product of the absolute index of refraction of water and the speed of light in water?

(1) frequency of light in water
(2) sine of the angle of incidence
(3) speed of light in a vacuum
(4) wavelength of light in a vacuum