PLEASE HELP, OVERDUE ASSIGNMENT!!

Cassy shoots a large marble (Marble A, mass: 0.06 kg) at a smaller marble (Marble B, mass: 0.03 kg) that is sitting still. Marble A was initially moving at a velocity of 0.7 m/s, but after the collision it has a velocity of −0.2 m/s. What is the resulting velocity of marble B after the collision? Be sure to show your work for solving this problem along with the final answer.
I need help because this doesn't make sense to me!! -O-
Please explain in not-gibberishhh! TvT
(It's not multiple choice)

An ideal spring has a spring constant (force constant) of 2500 n/m, is stretched 4.0 cm, how much elastic potential energy does it possess? (a) 3j (b) 0.00j (c) 1j (d) 2j (e) 4j

1134567 a jet with mass m = 1.1 ă— 105 kg jet accelerates down the runway for takeoff at 2 m/s2. 1) what is the net horizontal force on the airplane as it accelerates for takeoff? 2.2*10^5 n your submissions: 2.2*10^5 computed value: 220000submitted: saturday, january 26 at 2: 41 pm feedback: correct! 2) what is the net vertical force on the airplane as it accelerates for takeoff? 0 n your submissions: 0 computed value: 0submitted: saturday, january 26 at 2: 41 pm feedback: correct! 3) once off the ground, the plane climbs upward for 20 seconds. during this time, the vertical speed increases from zero to 21 m/s, while the horizontal speed increases from 80 m/s to 95 m/s. what is the net horizontal force on the airplane as it climbs upward? n 4) what is the net vertical force on the airplane as it climbs upward? n 5) after reaching cruising altitude, the plane levels off, keeping the horizontal speed constant, but smoothly reducing the vertical speed to zero, in 13 seconds. what is the net horizontal force on the airplane as it levels off? n 6) what is the net vertical force on the airplane as it levels off?

Three charge are arranged as shown in the diagram. the magnitude of the net electrical force acting on the +6 uc charge, rounded to the tenths place, is .