Hey guys.. ans me
a swimmer reaches the other bank of flowing river exactly opposite to the starting pt. if he was swimming at 2 kmh while maintaining 150 degree with the flow
then time taken by him to cross the river if 1km wide

  concave means having an outline or surface that curves inward like the interior of a circle or sphere. so the mirror curves inward.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j

Answer(b) both involve the use of levers;