The work done by external forces on the object can be calculated using the equation W = F x d, where F is the force applied and d is the distance moved.
Since the object has stopped, the distance moved is equal to the initial speed multiplied by the time taken to stop. Therefore, the work done by external forces can be calculated as:
W = F x (V x t)
Where V is the initial speed (6 m/s) and t is the time taken to stop.
Since the mass of the object is given (2 Kg), the force can be calculated using the equation F = m x a, where a is the acceleration. Since the object has stopped, the acceleration is equal to zero. Therefore, the force is also equal to zero.
Hence, the work done by external forces on the object is equal to zero.