If you put 300 J of heat into an engine with an efficiency of 0.35, how much work can be done? 3. How much energy must be put into an engine with an efficiency of 0.6 if 270 J of work are required? 4. An engine with an efficiency of 0.425 uses 1200 J of energy. Find the amount of energy wasted by the engine. 5. Calculate the efficiency of an engine operating between temperatures of 258 K and 600 K 6. An engine runs with its exhaust (cold) reservoir at a temperature of 200 K. To what temperature should the input (hot) temperature be set if an efficiency of 0.8 is desired? 7. Complete the following table of temperatures. Fahrenheit Celsius Kelvin 213 15 98.6 75 408
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.40 as a fraction is 4/10 or 2/5
the 4 is in the tenths place, so put it over a 10 to make it a fraction.
then, simplify the fraction by dividing the numerator and denominator by 2, and you get 2/5
Answer:
At 23.5 deg north of the equator this person would see the sun directly overhead at the summer solstice at noon
Answer:
Motion may be divided into three basic types — translational, rotational, and oscillatory.
Explanation:
Apply conservation of angular momentum:
L = Iw = const.
L = angular momentum, I = moment of inertia, w = angular velocity, L must stay constant.
L must stay the same before and after the professor brings the dumbbells closer to himself.
His initial angular velocity is 2π radians divided by 2.0 seconds, or π rad/s. His initial moment of inertia is 3.0kg•m^2
His final moment of inertia is 2.2kg•m^2.
Calculate the initial angular velocity:
L = 3.0π
Final angular velocity:
L = 2.2w
Set the initial and final angular momentum equal to each other and solve for the final angular velocity w:
3.0π = 2.2w
w = 1.4π rad/s
The rotational energy is given by:
KE = 0.5Iw^2
Initial rotational energy:
KE = 0.5(3.0)(π)^2 = 14.8J
Final rotational energy:
KE = 0.5(2.2)(1.4)^2 = 21.3J
There is an increase in rotational energy. Where did this energy come from? It came from changing the moment of inertia. The professor had to exert a radially inward force to pull in the dumbbells, doing work that increases his rotational energy.
