a boat travel due East with at 40metre per second across a river flowing due South 30metre per Second. what is the resultant speed of the boat

Explanation:

Use vector addition

v = √(30² + 40²) = 50 m/s as viewed from the shore

Trust me when I say I would never venture onto a river moving at 30 m/s no matter how powerful the boat was.

30 m/s(3600 s/hr / 1000 m/km) = 108 km/hr

The turbulence in water flowing over ground at 108 kilometers per hour would capsize anything ever built...including aircraft carriers.

These numbers are more suitable for a plane flying in air. Even that could be a very rough ride.

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the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.