- #1

OZwurld

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## Homework Statement

i need to calculate the power used up to carry a vehicle with 433mm diameter wheels,mass of 163kg up a slope of 3%. The horizontal distance of the slope is 2.9km. The surface of the slope is asphalt with rolling resistance of 0.22

From the following motor specs:

Rated Power = 1800 W

Nominal Speed = 1060 RPM

Nominal speed= 111 rad/s

Nominal torque = 16.2 Nm

Nominal Torque = 16.2 Nm

Continuous Torque = 42 Nm (5.0 kW)

## Homework Equations

P = Energy expended(E) / time (T);

where E = mgh*sin(α)

and T = height(H)/ average speed(Vavg);

## The Attempt at a Solution

P = mgHsin(α)/ (H/Vavg)

-> The H cancels and are left with

P = mg*Vavg*sin(α)

→ One of the problems i have is i don't know how to find the average velocity but i think:

Nominal speed * radius = m/s

∴Vavg = 111*0.5*433mm = 24m/s

∴ P = 163*9.81*sin(3%)*24

= 20W

→ i am also not sure what to do about the rolling resistance but i think:

Rolling resistance Force(Frr = mg*rolling resistace(Crr))

Frr = 163*9.81*0.22

= 351N

And i know W = F*d

∴W = 351*2.5km = 877.5KJ

and i know P = w/t

and that t = d/s = 2.9Km/24m/s = 120.8s

∴P = W/t = 877.5KJ/120.8 = 7.26KW

Dont know if i should add or subtract from the previous power...

PLEASE HELP ANY1...

Thanks in advance