Two blocks are arranged at the ends of a
massless string as shown in the figure. The
system starts from rest. When the 3.9 kg
mass has fallen through 0.322 m, its down-
ward speed is 1.29 m/s.
The acceleration of gravity is 9.8 m/s².
a
5.25 kg


3.9 kg

What is the frictional force between the
5.25 kg mass and the table?
Answer in units of N. Answer in units of
N.