Giant and supergiant stars are rare because

Magnetic fields are produced either by electric currents or time-varying electric fields. a. True b. False

An engine manufacturer makes the claim that the engine they have developed will, on each cycle take 100 J of heat out of boiling water at 100 °C, do mechanical work of 80J, and exhaust 20 J of heat at 10 °C.

A plane is flying east when it drops some supplies to a designated target below. The supplies land after falling for 10 seconds. How high above the ground was the airplane when the supplies were dropped? (Hint: d = 1/2gt2; g = - 9.

Friction is generated when?

If the intensity level at distance d of one trombone is 70 db, what is the intensity level of 76 identical trombones, all at distance d?

A world-class sprinter can burst out of the blocks to essentially top speed (of about 11.5 m/s) in the first 15.0 m of the race. what is the average acceleration of this sprinter, and how long does it take her to reach that speed?

How are primary and secondary succession similar and how are they different?

What relates the net force exerted on an object to its mass and acceleration?

I'm a wave, the medium moves parallel to the direction that the wave travels

What is the wavelength of a wave that has a velocity of 32 m/s and a frequency of 60.6 Hz?