Answer:
7.55 km/s
Explanation:
The force of gravity between the Earth and the Hubble Telescope corresponds to the centripetal force that keeps the telescope in uniform circular motion around the Earth:

where
is the gravitational constant
is the mass of the telescope
is the mass of the Earth
is the distance between the telescope and the Earth's centre (given by the sum of the Earth's radius, r, and the telescope altitude, h)
v = ? is the orbital velocity of the Hubble telescope
Re-arranging the equation and substituting numbers, we find the orbital velocity:

Be heavier
density=mass÷volume
if two items have the same size they have the same volume so the heavier one will be the denser one
Speed = (acceleration) x (time)
Velocity = (speed) in (direction of the speed)
Speed = (-3 m/s²) x (5 s) = 15 m/s
Velocity =
(15 m/s) in the direction opposite to the direction you call positive.
Displacement = (distance between start-point and end-point)
in the direction from start-point to end-point.
Distance = (1/2) (acceleration) (time)²
Distance = (1/2) (3 m/s²) (5 s)²
= (1/2) (3 m/s²) (25 s²) = 37.5 meters
Displacement =
37.5 meters in the direction opposite to the direction you call positive.