Answer:
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Explanation:
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The answer is 570 J. The kinetic energy has the formula of 1/2mV². The total work in this process W= 1/2m(V2²-V1²) = 1/2 * 15.0 * (11.5²-7.50²) = 570 J.
Answer:
1.58 W
Explanation:
Since the sound spreads uniformly in all directions, it must be in a form of a circle with radius of 12 m. So the area of the circle is

From the intensity of the sound we can calculate the power at 12 m

Answer:
Explanation:
It is given that Hair dryer , Toaster and coffeepot are working simultaneously with power 1200 W , 700 W and 800 W respectively.
So the total power of system is 
it is given that they work properly until toast is on.
By switching on the toast, appliance stop working because it may cause the circuit to break to safeguard the circuit.
Circuit breaker frame are used in home to prevent the short circuit
(A) A device that converts heat into work with 100% efficiency
It clearly violates the second law of thermodynamics because it warns that while all work can be turned into heat, not all heat can be turned into work. Therefore, despite the innumerable efforts, the efficiencies of the bodies have only been able to reach 60% at present.