The whole point of this problem is to check how well you understand
the definitions of a few important quantities, like velocity, speed, distance,
displacement etc.
Before we begin, I just want to mention that 'MPG' is not a unit of either
velocity or speed, but I think I know what you mean.
-- For some reason, Ms. Eaddy rode 100 miles north on the train, then
stayed aboard while the train turned around and took her 150 miles south.
The total distance she rode was (100 + 150) = 250 miles. But she ended up
50 miles south of where she began.
-- Displacement for the whole trip = distance and direction from the start point
to the finish point.
Displacement = 50 miles south
-- Average velocity = (displacement) / (time)
50 miles south / 3.5 hours = <u>14.29 miles per hour south</u>
Answer:
Part a)

Part b)

Explanation:
As we know that there is no external force on the system of two masses so here total momentum of the system will remains conserved
so we can say




Part b)
magnitude of the initial speed of A = 
magnitude of the initial speed of B = 
magnitude of final speed of A = 
magnitude of final speed of B = 
Now change in total kinetic energy is given as



I think it's a pulley and a lever.
The part that causes the disc caliper piston to retract when the brakes are released is the square-cut O-ring.
The square cut seal is the most important part of a disc brake caliper, for keeping the brake behind the piston so that when you step on the brake pedal, it releases a pressure that applied to the piston which in return applies the pad to the rotor.