A whale swimming under water at a speed of 27 km / h develops a power of 150 kilowatts.

| June 21, 2021 | education

A whale swimming under water at a speed of 27 km / h develops a power of 150 kilowatts. Find the strength of the water resistance to the movement of the whale.

V = 27 km / h = 7.5 m / s.

N = 150 kW = 150,000 W.

Fsopr -?

Since the whale moves uniformly with a constant speed V = 7.5 m / s, then according to 1 Newton’s law, the action of all forces on it is compensated. The thrust force Ft, which the whale develops when moving, is equal to the water resistance force Fcop: Ft = Fcop.

Let us express the power of the whale N by the formula: N = A / t, where A is the work of the whale while moving, t is the time of work.

A = Ft * S, where S is the movement of the whale while moving.

Since it moves evenly, then S = V * t.

N = Fcopr * V * t / t = Fcopr * V.

Fcopr = N / V.

Fcopr = 150,000 W / 7.5 m / s = 20,000 N.

Answer: when the whale moves, the resistance force Fcopr = 20,000 N.



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