Final answer:
The torque needed to keep the pirate from falling into the water is 1764 N"m.option D.
Step-by-step explanation:
To calculate the torque needed to keep the pirate from falling into the water, we can use the formula:
Torque = Force x Distance
The force acting on the pirate is the weight of the pirate, which is equal to the mass of the pirate multiplied by the acceleration due to gravity.
Weight = mass x g
The distance is the distance from the gunwale to the end of the plank.
Plugging in the given values, we have:
Weight = 90 kg x 9.8 m/s² = 882 N
Torque = 882 N x 2 m = 1764 N"m
Therefore, the torque needed to keep the pirate from falling into the water is 1764 N"m (option d).