The middle one on the list is the correct one.
The first one ... distance divided by time ... is Speed, not force.
The third one ... mass times velocity ... is Momentum, not force.
They are speed and direction.
Answer:
4
Explanation:
G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²
= Mass of Earth
= Mass of Moon
r = Distance between Earth and Moon
Old gravitational force

New gravitational force

Dividing the equations

The ratio is 
The new force would be 4 times the old force
a = ( v(2) - v(1) ) ÷ ( t(2) - t(1) )
2 = ( v(2) - 10 ) ÷ ( 6 - 0 )
2 × 6 = v(2) - 10
v(2) = 12 + 10
v(2) = 22 m/s