Answer:
3.7 km/h
Explanation:
Let's call v the proper speed of the boat and v' the speed of the water in the river.
When the boat travels in the direction of the current, the speed of the boat is:
v + v'
And it covers 50 km in 3 h, so we can write
(1)
When the boat travels in the opposite direction, the speed of the boat is
v - v'
And it covers 50 km in 5.4 h, so
(2)
So we have a system of two equations: by solving them simultaneously, we find the value of v and v':

Subtracting the second equation from the first one we get:

So, the speed of the water is 3.7 km/h.
You should put when you will leave, where you will be, and what time you will get back.
Answer:
it will move towards the object's magnetic south
Explanation:
The compass pints towards the earth geographic north because the magnetic south of the earth's magnetic field is located in there, if you placed such compass neaar the piece of ferromagnetic material, the magnetic field produced by the magnet will make the compass needle point towards its south magnetic pole, in the same fashion as it points to the earth's magnetic south. It will point to the object's south pole because the magnetic field will be stronger than the earth's (which is weak) that is because of the way magnetism works, opposite poles are attracted and similar poles will tend to separate from each other
I think the question meant to say net force on the box. Since force is a vector, the direction matters. 20N left is negated completely by the 50N right, which means the net force is 50N-20N to the right, 30N.