A large cruise ship of mass 6.50*10^7 kg has a speed of 12.0 m/s. What is the ship's kinetic energy, how much work is required to stop it and if it has to be stopped over 2.5 km what is the force to be applied.
The mass of the ship is 6.5*10^7 kg and it is moving at a speed of 12 m/s.
The kinetic energy of the ship is given by K.E. = (1/2)*m*v^2
=> 4.68*10^9 J
To stop the ship the work required to be done is equal to the kinetic energy of the ship or 4.68*10^9 J
Work = force*distance; to stop the ship over a distance of 2.5 km or 2500 m the force that would have to be applied is equal to 4.68*10^9/2500 = 1.872*10^6 N