- #1
Mike Gaffer
- 24
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I'm working on making a model car, and am trying to calculate the torque required to accelerate the car from a stop to 1.22m/s in 1 second, so I can pick out the right DC motor...
The acceleration required is 1.22m/s/s (~ 4ft/s)
The weight of the car is 0.85 kg
The drive wheels diameters are 0.03175 m (1.25") [wheel circ 0.099746m]
I do not have to take into account wind resistance, frictional resistance, gear box ratios (yet), drive train friction, etc. (this is still a preliminary calculation)...
I WOULD like to take into account the angular momentum ... and am going to have to have some worm gear or gear box reduction (didn't get that far yet)...
So far, I did:
velocity (final) = 1.22m/s (in time = 1s)
= 1.22 m/s^2 acceleration
rpm of wheel = (velocity of car) / dist wheel travels in 1 rotation [circum.]
= (1.22m/s) / 0.099746 m
= 12.22 rps
= 733.4 rpm
ω = rpm x 2pi / 60
= 733.4 x (2pi / 60)
= 76.80093 rad/s
P = W/t = KE / t = 1/2 mv^2/t [power = work/time]
= 0.632 watts?
= E[J] = P[watts] x t[sec] = 0.632 Joules... ? <---- where does ω come into this?
ALSO, 0.632 watts seems like way too little power required... did I miss something?
THANKS IN ADVANCE!
The acceleration required is 1.22m/s/s (~ 4ft/s)
The weight of the car is 0.85 kg
The drive wheels diameters are 0.03175 m (1.25") [wheel circ 0.099746m]
I do not have to take into account wind resistance, frictional resistance, gear box ratios (yet), drive train friction, etc. (this is still a preliminary calculation)...
I WOULD like to take into account the angular momentum ... and am going to have to have some worm gear or gear box reduction (didn't get that far yet)...
So far, I did:
velocity (final) = 1.22m/s (in time = 1s)
= 1.22 m/s^2 acceleration
rpm of wheel = (velocity of car) / dist wheel travels in 1 rotation [circum.]
= (1.22m/s) / 0.099746 m
= 12.22 rps
= 733.4 rpm
ω = rpm x 2pi / 60
= 733.4 x (2pi / 60)
= 76.80093 rad/s
P = W/t = KE / t = 1/2 mv^2/t [power = work/time]
= 0.632 watts?
= E[J] = P[watts] x t[sec] = 0.632 Joules... ? <---- where does ω come into this?
ALSO, 0.632 watts seems like way too little power required... did I miss something?
THANKS IN ADVANCE!
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