Question:medium

The tractor develops a torque of 35 kg-m at an engine speed of 1350 RPM. Calculate the BHP of the tractor.

Show Hint

Use the torque-power-speed relation for a rotating shaft, keeping torque in kgf-m and speed in RPM, to directly get horsepower.
  • 45
  • 66
  • 90
  • 77
Show Solution

The Correct Option is B

Solution and Explanation

Convert the torque to SI units first and compute power in watts, then change to horsepower, as a cross-check on the direct formula. Torque \(T = 35\ \text{kgf-m} = 35 \times 9.81 = 343.35\ \text{N-m}\). Angular speed \(\omega = \dfrac{2\pi N}{60} = \dfrac{2\pi \times 1350}{60} = 141.37\ \text{rad/s}\).
Power \(P = T\omega = 343.35 \times 141.37 \approx 48540\ \text{W} = 48.54\ \text{kW}\).
Convert to horsepower using \(1\ \text{kW} = 1.341\ \text{HP}\):
\[\text{HP} = 48.54 \times 1.341 \approx 65.1\]
This matches the direct metric-horsepower calculation closely, confirming the result.
\[\boxed{\text{BHP} \approx 66}\]
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