I am having trouble getting the answer for this one. The question is about two students moving a piano. The piano weighs 260kg and one student is pushing with 280N Forward and the other 340N Forward. The piano is accelerating at 0.30m/s^2 Forward.
They are asking for kinetic friction as well as how long it will take for the piano to stop moving after pushing it for 6.2 seconds from rest
The Attempt at a Solution
So far I have tried adding the two students Newtons and then diving the weight of the piano (times gravity) which gives me 2548. Then I divide by the ammount of Newtons the students are applying on the piano (Forward) which is 620N (combined) by 2548
The answer I get is around 0.24 for the coefficient of kinetic friction. The back of the book says 0.21. Could someone please tell me what I am doing wrong, and possibly how I could go about finding the second part of the question. Thanks.