D. Equal to zero.
Because the forces balance each other.
Answer:
Missing numbers are 3,11,13, 15,17,19, 23,27,29 and wrong are 6,68
As the first astronaut throws the ball, lets assume it goes with v velocity and the mass of the ball be m
the momentum comes out be mv, thus to conserve that momentum the astronaut will move opposite to the direction of the ball's motion with the velocity mv/M (where M is the mass of the astronaut).
A closed circle means the number is included and an open circle means its not.
