Knowing that slider block A starts from rest and moves to the left with a constant acceleration of 1 ft/s2 , determine (a) the relative acceleration of block A with respect to block B, (b) the velocity of block B after 2 s

Indoraptor for sure

Planck decided to assume that atoms could only vibrate at certain frequencies that were whole numbers eg 2f, 3f and so on. others used to think that atoms vibrate continuously

I'm having some difficulty seeing the diagram clearly.but the question says there's a net inward force on the object.so we know right away,  from newton's 2nd law of motion, thatthat baby is accelerating.  it doesn't even matter which way thenet force is pointing.  if there's any net force, then either theobject's speed or else its direction must be changing.