Three people talk simultaneously. If the intensity level is 92 dB when either one speaks alone, what is the intensity level when both speak at once?

Two converging lenses are separated by 29.00 cm. The focal length of each lens is 17.00 cm. An object is placed 32.00 cm to the left of the lens that is on the left. Determine the final image distance relative to the lens on the right.

5 kg of saturated liquid water at 10 bars is contained in a piston-cylinder assembly and undergoes two processes. process 1-2: heated at constant pressure until it is saturated vapor. process 2-3: cooled as it is compressed at constant volume until it reaches 110 degrees celsius. determine the overall work and heat transfer for these processes. Hint: Must used linear interpolation from values in the correct Water tables.

you have a toy car running on two batteries. if you could hook it up wit only one of the batteries, it would draw

a)twice as much current as the two batteries

b) half as much current as the two batteries

c) the same amount of current as the two batteries

why??

A fullback with a mass of 116 kg and a velocity of 2.7 m/s due west collides head-on with a defensive back with a mass of 89 kg and a velocity of 6 m/s due east.
(a) What is the magnitude of the fullback's initial momentum?
(b) What is the direction of the fullback's initial momentum?
(c) What is the magnitude of the defensive back's initial momentum?
(d) What is the direction of the defensive back's initial momentum?
(e) What is the magnitude of the total momentum of the system?
(f) If they stick together and external forces can be ignored, what direction will they be traveling immediately after they collide?

Using Maxwell's equations and the variety of forms, how do you think that such a wave can self-propogate without a constant source of radiation?

Helmholtz coils are frequently used in experiments because they create a uniform magnetic field about their central axis. For example, they are traditionally used in the experiment for the measurement of the charge‑to‑mass ratio of the electron. Helmholtz coils are two coils separated by a distance equal to their radius and also carry equal currents in the same direction, as shown in the figure. Suppose the radius of the coils is ?=16.50 cm R=16.50 cm and each coil carries a current of ?=15.50 AI=15.50 A and has ?=500.0 turns.N=500.0 turns. The coils are in the ??yz plane where one coil's center is at ?=0 x=0 the other coil's center is at ?=?.x=R.

Using the Biot–Savart law, determine the expression for the resultant magnetic field ??Bx along the line ?x joining their centers. Express the magnetic field in terms of the radius of the coils ?,R, the number of turns ?,N, the current ?,I, ?,x, and the permeability of free space, ?0.

Bx= ?

Evaluate the magnetic field ??Bx at ?=4.125 cm x=4.125 cm (14?)(14R) and ?=12.38 cm x=12.38 cm (34?).

1. Based on what you heard in this podcast, do you think you are "frying your brain" with your cell phone? Why or why not?

A man of mass 80 kg runs up a flight of stairs 20 m high in 10 s. (a) how much power is used to lift the man? (b) If the man’s body is 25% efficient, how much power does he expend? (c) This man consumes approximately 1.05 × 107 J (2500 food calories) of energy per day while maintaining a constant weight. What is the average power he produces over a day? (d) Compare this with his power production when he runs up the stairs.

Answer is: a) 1.6 kW; (b) 6.3 kW; (c) 122 W; (d) 1.9% of power produced running up stairs

Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 3.6 m/s² for 4.4 seconds. It then continues at a constant speed for 8.2 seconds, before applying the brakes such that the car

Find the electric field at the location of q_a in the figure below, given that q_b = q_c = q_d = +1.85 nC, q = ?1.00 nC, and the square is 11.5 cm on a side. (The +x axis is directed to the right.)

A 0.190-kg cube of ice (frozen water) is floating in glycerine. The gylcerine is in a tall cylinder that has inside radius 3.60 cm . The level of the glycerine is well below the top of the cylinder. If the ice completely melts, by what distance does the height of liquid in the cylinder change?

A beam of unpolarized light with intensity 170 W/m^2 is incident on a pair of ideal crossed (perpendicular) polarizers. You insert a third ideal polarizer between the two polarizers with its polarizing axis at 45∘ to the others. Determine the intensity of the emerging light after you insert the third polarizer. Express your answer with the appropriate units.

On February 23, 1987 astronomers noticed that a relatively faint star in the Tarantula Nebula in the Large Magellanic Cloud suddenly became so bright that it could be seen with the naked eye. Astronomers suspected that the star exploded as a supernova. Late-stage stars eject material that forms a ring before they explode as supernovas. The ring is at first invisible. However, following the explosion the light from the supernova reaches the ring. Astronomers observed the ring exactly one year after the phenomenon itself occurred (Figure 1). The angular size of the ring is 0.81 arcseconds.

Use geometry and the speed of light to estimate the distance to the supernova.