A 2kg block slides on a horizontal surface with an initial speed of 10ms−1. For the first 3m the coefficient of kinetic friction is 0.10, and for the next 5m it is 0.25. What is the speed of the block after it has completed the total 8m? (Take g=10ms−2.)
a) 8.5ms−1
b) 6.2ms−1
c) 7.7ms−1
d) 8.3ms−1