Answer:
0.41
Explanation:
A 49 N block has a mass of 5 kg:
49/9.8
A horizontal force of 50 N giving it an acceleration of 6 m/s^2 means that 30 N is taken up by the acceleration
This leaves 20 N to take care for friction. so the coefficient of friction is:
20/49 = 0.41.
