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 engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 26 mm and 103 mm. the electric potential of the inner conductor with respect to the outer conductor is - 700 v (k = 1/4πε 0 = 8.99 × 109 n · m2/c2) the energy stored in a 1.0-m length of this capacitor is closest to

What is the difference between mass density and weight density?