Please answer these questions, thanks!

2. A 2 kg mass travelling at 8 m/s [ W ] collides head on in an elastic collision (in a closed system) with a 4 kg mass travelling at 4 m/s [E]. Determine the velocity of each mass after the collision. (6 marks) 3. A toy dart of mass .1 kg is loaded in a toy dart gun. A spring (k = 250 N/m) is compressed 6.0 cm and then released (8 marks) a) How much work was required to load the dart? b) How fast is the dart travelling when it leaves the gun (assume spring has returned to original length) c) If the dart was shot horizontally from a height of 2.0 m how fast is it travelling as it hits the ground? Use your choice of methods 4. A 50 kg parkour artist jumps vertically upward from the top edge of a platform with a speed of 5.0 m/s. (6 marks) a) Determine how fast the artist is travelling as she lands on a second platform located 3.0 m below the first platform using your energy techniques b) Confirm your answer using kinematics.