Alarge cruise ship of mass 6.40 ✕ 107 kg has a speed of 11.6 m/s at some instant. (a) what is the ship's kinetic energy at this time? j (b) how much work is required to stop it? (give the work done on the ship. include the sign of the value in your answer.) j (c) what is the magnitude of the constant force required to stop it as it undergoes a displacement of 3.20 km? n

(a)

The kinetic energy of an object is given by:

where

m is the mass of the object

v is its speed

For the ship in the problem, we have

is the mass

is the speed

So its kinetic energy is

(b)

According to the work-kinetic energy theorem, the work done on an object is equal to the change in kinetic energy of the object:

where

W is the work done

m is the mass of the object

v is the final speed of the object

u is the initial speed of the object

Here we want to find the work done to stop the ship, so the final speed of the ship is v=0, while the initial speed is u=11.6 m/s. So the work done will be

(c)

The work done on an object can be also written as follows

where

F is the magnitude of the force

d is the displacement of the object

Here we know:

is the work done

d = 3.20 km = 3200 m is the displacement of the ship

So we can solve the formula to find F, the force exerted on the ship to stop it:

and the negative sign simply means that the force is opposite to the displacement of the ship (in fact, the force acts against the motion of the ship).

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this