The minimum amount that one stimulus can differ from another with the difference still being noticed is referred to as the

Not really physics, but more psychology. The difference is known as least perceptible difference.

All are great precautions but you can still lift lighter and different muscles in between hard workdays. this keeps other muscles not usually used in shape.

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.