In this case we will calculate the power required for starting motion from rest and reaching a maximum speed of 10 km/hr (on the 2nd shift).
Normal force is calculated using the approximated weight discussed in the previous section, which is approximated to be 48 kg on each of the two rear wheels.
Fn= m x g = 48 x 9.8 = 470.4 N
Fs= Crr x Fn = 0.0055 x 470.4 = 2.587 N (total frictional force)
ii. Torque Calculation
Acceleration is assumed to be 0.3 m/s^2 as above. Therefore using newtons law will give us:
Required Force - Frictional Force = Mass x Acceleration
Required Force= (48 x 0.3) + 2.587 = 16.987 N
Using the torque equation and the wheel radius of 13 in (obtained from available wheels in the market) we will were able to calculate the torque as the following:
Torque = Force x Raduis = 16.752 x 0.3302 = 5.609 Nm
Total Torque = 2 x 5.609 = 11.218 Nm
iii. Power Calculation
Rotational speed required is calculated according to the objective of reaching a maximum speed of 10 Km/hr (on 2nd shift).
Rotational Speed = Speed / Raduis = 2.777 / 0.3302 = 8.412 rad/s = 80.332 rpm
Power = Torque x Rotational Speed = 11.218 x 8.412 = 94.373 W
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