Consider a 1200 kg car and solve the questions below (worth 30 marks).

 

 

 

 

 

a)

Find

the

cost

of

transportation

(per kilometre)

in

units

of

MJ/km

if

this car

drives

1

kilometer at an average speed of

15

m/s (54 kph).

Draw a simple car

showing the cross section and 3 arrows to identify the direction of the movement and forces. Assume:

h

= 21% engine;

stops and starts 5 times per km (city driving);

C

rr

=0.025

cross

section is 3.5m

by 2.55m;

C

d

=0.32; air density 1.29

kg/m

3

.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b)

Convert this cost of transportation from MJ/km into