A 3 kg block rests on a rough horizontal table. A rope is
attached to the block and is pulled with a force of 11N to the
left. As a result, the block accelerates at 3 m/s2. The coefficient
of kinetic friction uk between the block and the table is __
(round to the nearest hundredth)

Ireally don’t know

Distance covered = speed x timethe distance traveled going against the stream = distance traveled with the stream.therefore it is the speed and the time that are the variables.as he travels the same distance both ways, speed x time is the same for each way.going upstream his speed is 4 kph; going downstream his speed is 6 kph.therefore we have two simultaneous equations: time upstream x 4 = time downstream x 6time upstream + time downstream = 60 minutestherefore we have the equation: time upstream = 6/10 hour, time downstream therefore = 4/10 hour.distance traveled at 4km/hr in 6/10 hour = 24/10 = 2.4km.check: distance traveled at 6km/hr in 4/10 hour = 24/10 = 2.4km.

The answer to the question is (a)   

The fuzzy edges of shadows are a result of  diffraction