Potential and kinetic energy along with an external force
Answer: 0.42 km/min
Explanation:
total distance traveled(in meters) = 210m
total distance traveled(in km) = 210 ÷ 1000 = 0.21 km
total time taken(in seconds) = 30 s
total time taken(in minutes) = 30 ÷ 60 = 0.5 s
speed =(distance traveled)÷(time taken)[in km/min] = 0.21 ÷ 0.5 = 0.42km/min
Answer:
<em>The comoving distance and the proper distance scale</em>
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Explanation:
The comoving distance scale removes the effects of the expansion of the universe, which leaves us with a distance that does not change in time due to the expansion of space (since space is constantly expanding). The comoving distance and proper distance are defined to be equal at the present time; therefore, the ratio of proper distance to comoving distance now is 1. The scale factor is sometimes not equal to 1. The distance between masses in the universe may change due to other, local factors like the motion of a galaxy within a cluster. Finally, we note that the expansion of the Universe results in the proper distance changing, but the comoving distance is unchanged by an expanding universe.
Answer:
The angular speed of the system increases.
The moment of inertia of the system decreases.
Explanation:
As we know that the girl is going towards the center of the circle so here the moment of inertia of the girl is given as

here we know that
r = position of the girl from the center of the disc
now we know that the girl is moving towards the center so its distance will continuously decreasing
So the moment of inertia of the girl will decrease
Now we know that that with respect to the center of the disc there is no torque on the disc + girl system
So here we can use angular momentum conservation
So we have

since moment of inertia is decreasing for the system
so angular speed will increase