Which pair of objects will have the least gravitational attraction to each other

a: 2 concrete blocks 6 cm apart
b: 2 marbles 12 cm away
c: a concrete block and a marble 6 cm apart
d: a concrete block and a marble 12 cm apart

An object thrown vertically upward from the surface of a celestial body at a velocity of 36 m/s reaches a height of sequalsminus0.9tsquaredplus36t meters in t seconds. a. determine the velocity v of the object after t seconds. b. when does the object reach its highest point? c. what is the height of the object at the highest point? d. when does the object strike the ground? e. with what velocity does the object strike the ground? f. on what intervals is the speed increasing?

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat

Aball of mass 0.3kg is released from rest at a height of 8m.how fast is it going when it hits the ground? accleration due to gravity is g=9.8m/s