a steam engine work on its vicinity 285 k heat is released with the help of 225 c energy absorbed to the system what is the effi
2 answers:
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Answer:
1) 883 kgm2
2) 532 kgm2
3) 2.99 rad/s
4) 944 J
5) 6.87 m/s2
6) 1.8 rad/s
Explanation:
1)Suppose the spinning platform disk is solid with a uniform distributed mass. Then its moments of inertia is:
If we treat the person as a point mass, then the total moment of inertia of the system about the center of the disk when the person stands on the rim of the disk:
2) Similarly, he total moment of inertia of the system about the center of the disk when the person stands at the final location 2/3 of the way toward the center of the disk (1/3 of the radius from the center):
3) Since there's no external force, we can apply the law of momentum conservation to calculate the angular velocity at R/3 from the center:
4)Kinetic energy before:
Kinetic energy after:
So the change in kinetic energy is: 2374 - 1430 = 944 J
5)
6) If the person now walks back to the rim of the disk, then his final angular speed would be back to the original, which is 1.8 rad/s due to conservation of angular momentum.
Answer:
D) 720 kmph
Explanation:
First, let's find what distance this aeroplane covered. Distance (d) is the product of speed and time - here, we have a speed of 240 kmph and a time of 5 hours, gives us
km
Using that same fact, we can set up a new equation to solve for speed (s) when we have a distance of 1200 km and a time of 1 2/3 hours. For the sake of cleanliness, I'm gonna rewrite 1 2/3 as the improper fraction 5/3:
Multiplying both sides of the equation by 3/5:
kmph
So our answer is D.