I believe Amany was referencing slide 194 when we are calculating the normal force.  It looks as though the equation was copied from the previous part d, but the value not updated to 3.96 m/s.

Brenda, thanks for the clarification, and you and Amany are right.  Amany, sorry I misunderstood your question. I just replaced the v bottom with v top and changed the answer. I've updated the presentation, and will re record that slide shortly.  John

The units on slide 150 are m/s^2. The units should be m/s. 
Thanks,
Nick Hudson

Nick,

I wonder if you're using an old saved version - the most current one looks like it has the right unit.  Please let me know.

John