To give a 19kg child a ride, two teenagers pull on a 3.7 kg sled with ropes, as indicated in the figure. Both teenagers pull with a force of 55N at an angle of 35 degrees relative to the forward direction, which is the direction of motion. In addition, the snow exerts a re t a r d i n g force on the sled that points opposite to the direction of motion, and has a magnitude of 57N, find the acceleration of the sled with the child.

The answer is frictional force

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