PLEASE HELP ASAP - MULTIPLE QUESTIONS - 100 pts!

1. A single 1,000 kg train car moving at 5.0 m/s collides with the back of two 1,000 kg train cars linked together. It latches onto the car it strikes as the two parts of the coupled cars exert forces on each other. What is the speed of the cars immediately afterward?

2. A firecracker stuck into a 150 g apple explodes and sends five apple fragments in different directions. The vector sum of momenta 1, 2, 3, and 4 is found from a video of the event to have components px = 1.20 kg m/s, py = 0.80 kg m/s (with no other component). The mass of the fifth fragment is 0.050 kg. What is its velocity right after the explosion? (Picture is provided)

3. A 1,600 kg car traveling north at 10.0 m/s crashes into a 1,400 kg car traveling east at 15 m/s at an unexpectedly icy intersection. The cars lock together as they skid on the ice. What is their speed after the crash?