Frame and Design Table 6-2 Hill-Climbing Force Fh for 15 Different Values of Incline
Degree of incline 1% 2% 3% 4% 5% 6% 8% 10% 15% 20% 25% 30% 35% 40% 45%
Incline angle O 0° 34' 1° 9' 1° 43' 2° 17' 2° 52' 3° 26' 4° 34' 5° 43' 8° 32' 11° 19' 14° 2' 16° 42' 19° 17' 21° 48' 24° 14'
sin O 0.00989 0.02007 0.02996 0.04013 0.05001 0.05989 0.07062 0.09961 0.14838 0.19623 0.24249 0.28736 0.33024 0.37137 0.41045
Fh (in pounds) 9.9 20.1 29.6 40.1 50.0 59.9 79.6 99.6 148.4 196.2 242.5 287.4 330.2 371.4 410.5
a (in mph/sec)
1
2 3 4 5 6
From Build Your Own Electric Vehicle, Table 5-1, p. 101.
Weight Affects Speed Although speed also involves other factors, it is definitely related to weight. Also, horsepower and torque are related to speed per Equation 3: hp 5 FV/550 where hp is motor horsepower, F is force in pounds, and V is speed in feet per second. Armed with this information, Newton’s second law equation can be rearranged as a 5 (1/M) 3 F and because M 5 W/g (Eq. 10) and F 5 (550 3 hp)/V, they can be substituted to yield a 5 550(g/V)(hp/W) Finally, a and V can be interchanged to give V 5 550(g/a)(hp/W) where V is the vehicle speed in feet per second, W is the vehicle weight in pounds, g is the gravitational constant (32.2 ft/s2), and the other factors you’ve already met. For any given acceleration, as weight goes up, speed goes down because they are inversely proportional.
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