Answer:
9.8J
Step-by-step explanation:
The work done by the friction force can be calculated as
W = Fd
Where F is the friction force, and d is the distance that the block slide.
So, replacing F = 1.4 N and d = 7 m
W = (1.4N)(7 m)
W = 9.8 J
Therefore, the work done by the friction was 9.8J against the movement of the block