What is the mass of a black hole which has the radius of the sun(696,340 km).

It has a diameter of about 78 billion miles. For perspective, that's about 40% the size of our solar system, according to some estimates. And it's estimated to be about 21 billion times the mass of our sun. So there you have it, black holes can be millions of times larger than suns and planets or as small as a city.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s