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Torque value needed to move a particular vehicle

  1. Dec 3, 2015 #1
    can i know how much torque is required to move a 200kg weighed vehicle to 30kmph by using 24v, 250w dcmotor
  2. jcsd
  3. Dec 3, 2015 #2


    Staff: Mentor

    Welcome to Physics Forums

    The answer depends on how much acceleration and how much friction. You did not supply enough information for us to answer.
  4. Dec 3, 2015 #3
    acceleration: 1.3m/s2
    coefficient of friction: 0.02
    wheel radius:8inch
  5. Dec 3, 2015 #4


    Staff: Mentor

    OK, I'm rusty but I'll take a crack.

    Acceleration ##F = m*a = 1.3 m/s^2 * 200 kgm = 260 newtons = 26.5 kgf##
    Rolling resistance ##200 kgf * 0.02 = 4 kgf## (assume air resistance is zero)
    Total force, ##30.5 kgf##

    The wheel radius is 8" or 0.2 m.
    Torque = ##30.5 kgf * 0.2 m = 6.1 kgf*m = 60 n*m##
    60 newton meters torque is my answer.

    The fact that torque is supplied by a motor is irrelevant.
  6. Dec 3, 2015 #5


    User Avatar
    Science Advisor

    If the acceleration is maintained all the way up to the peak speed of 30 km/h (8.3 meters/sec) then that's 300 Newtons times 8.3 meters/sec ~= 2500 watts. That's an awful lot to expect from a 250 watt motor.

    If we assume, instead, that we are just supplying the 40 Newtons required to match rolling resistance then that's 40 Newtons times 8.3 meters/sec = 333 watts. That's still going to be pretty tough on the motor even without factoring in air resistance.
  7. Dec 4, 2015 #6
    i noticed for tata nano car (i c engine) weighing 680kg needs only 51 n-m torque to accelerate to 60kmph in 10 sec can we compare the both in the case of torque required
  8. Dec 4, 2015 #7


    User Avatar
    Science Advisor

    IC Motor specs are generally given at the flywheel so any gearing is ignored. The torque value at the engine means little as it can be easily changed with the gear box. What matters is power output as, ignoring drive train losses, power is constant for any gear/wheel size/final drive etc
  9. Dec 7, 2015 #8
    thanks for your help
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