Ahelicopter rescues a 105kg shipwreck survivor by lifting him straight up. survivor moved 15 m up while his speed drops from 4m/s to 0. what is the work done on home by the applied force?

16275 Joule

Explanation:

Work Done By A Constant Force

The work can be computed as

W=F.X, where F is the applied force (in this case, the force needed to overcome gravity)

Recall the second Newton's law which states that

Being the net force on a system of mass m and acceleration a

We know the helicopter is applying force against gravity because the speed of the shipwreck survivor changes from 4 m/s to 0 m/s in 15 meters

Let's calculate that acceleration by using the dynamics equation

Solving for a

a=-0.533\ m/sec^2

The negative sign indicates the body is braking, we'll later use the magnitude

The net force is, then

The only two forces acting upon the survivor is the lifting force of the helicopter and the weight of the man, so

Finally, the work done by the helicopter is

The work done by the helicopter is

the answer would be c. motion and direction

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