Cart a is moving at 2 m/s and cart b is at rest. after a perfectly elastic collision (cart a is stationary after the collisions), how fast will cart b move? both carts have a mass of 1 kg

i guess it’s a and b

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles