Answered Questions

  • Thermal Efficiency

    Why the thermal efficiency of the engine decreases at part load?


    • Jul 26th, 2009

    There are always some mechanical losses in the engine while running. These losses are more or less same at all the speeds. When the speed decreases, the output will obviously decreases. But, the losses remain same. So, the overall efficiency also decrease.

  • Speed and Torque

    What is the practical difference Speed and Torque?


    • Dec 7th, 2013

    The first cyclist gives his force alone but, the second cyclist gives his force with addition to the rider behind, the second cyclist have the tendency to give more torque than first cyclist.

  • Torsion- Shafts

    Why do we use solid shafts for transfer of power in case of pumps/ turbines & other machines why we use a hollow shaft (pipe) in universal joints of automobiles; although the rated load and twist is approx. the same.

    Arun Govind Neelan

    • Feb 27th, 2012

    In automobile application we have to consider weight in addition to torque and strength. Hollow shaft has high torque transmitting capacity per unit mass compared to solid shaft. If you consider bending stress diagram for hollow it is min at centre so material requirement is minimum at centre.