Final answer:
The work done by friction on the block between point A and B is 1.75 J, which is negative indicative of the energy loss to friction.
Step-by-step explanation:
The amount of work done by friction as a block slides from point A to point B is given as 1.75 joules (J). When friction does work against the motion of an object, the work is considered to be negative because it is in the opposite direction of the displacement.
The formula for the work done by friction is Wfr = Ffrd cos(180°), where Wfr is the work by friction, Ffr is the friction force, d is the displacement, and the cos(180°) reflects that the force and displacement are in opposite directions.
Given that work by friction is -4.00 J in a case where the friction force is 5.00 N and the displacement is 0.800 m, one could infer that the negative work represents the energy loss to friction.
The work done by friction can be calculated using the equation:
Wfr = -Ffrd
Where Ffr is the force of friction and d is the displacement. In this case, the work done by friction is -4.00 J.