A transformer can only operate if _________
a. the power in equals the power out
b. the potential difference is large enough
c. a.c. is used
d. we step up the voltage
c
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In space, a 4.0 kg metal ball moving 30. m/s has a head-on collision with a stationary 1.0 kg second ball. After the elastic collision, what are the velocities of the balls?
What will be an ideal response?
A fan, electric heater, and lamp are connected in parallel across a 120-V line. The resistances are Rlamp = 148 ?, Rheater = 32 ?, and Rfan = 48 ?. What is the total current supplied to the circuit?
a. 17.0 A b. 7.06 A c. 0.526 A d. 1.90 A
On his honeymoon, James Joule attempted to explore the relationships between various forms of energy by measuring the rise of temperature of water which had fallen down a waterfall on Mount Blanc
What maximum temperature rise would one expect for a waterfall with a vertical drop of 20 m? The specific heat of water is 4186 J/kg ? K. A) 0.047 C° B) 0.064 C° C) 0.053 C° D) 0.071 C°
An astronaut is traveling at a high rate of speed from the Earth to a distant star system. Observers here on Earth note the relativistic effect that the astronaut's clocks run slow. What relativistic effect, if any, does the astronaut observe?
a. Her pulse rate slows. b. The distance from the Earth to the star system has decreased. c. Her clocks run faster. d. There is no relativistic effect to be observed by the astronaut since she is the one doing the moving.