National Standard Examination in Astronomy (NSEA) Solved Paper 2016 Part-21

Q: 74. Passage question 74-76

Consider a spacecraft in an elliptical orbit around the earth. At the low point or perigee of its orbit it is 400 km above the earth’s surface. At the high point or apogee it is 4000 km above the earth’s surface. The period of the space craft’s orbit is (g=9.8 and R=6400 km)

(A)

(B)

(C)

(D) 3

Q: 75. The ratio of speed of the spacecraft at perigee to its speed at apogee is almost equal to

(A)

(B)

(C)

(D)

Q: 76. The speed of the satellite at perigee is

(A) 8576

(B) 57.307

(C) 5876

(D) 7856

Q: 77. Astronomers believe that a large percentage of the mass of the universe is dark matter. In one recent study the transverse velocity of the large Magellanic cloud (LCM) was measured to be 200 the LMC is believed to orbit the centre of our galaxy at about Assuming a circular orbit percentage of dark matter in our galaxy is about (independent estimate of visible matter is )

(A) 77%

(B) 82%

(C) 70%

(D) 80%

Q: 78. The escape speed from Jupiter is approximately and its radius is about 12 times that of earth. From this we may estimate the mean density of Jupiter to be about (Radius of earth = cape speed from the earth is )

(A) 5 times that of earth

(B) 0.4 times that of the earth

(C) 2.5 times that of the earth

(D) 0.4 times that of the earth