Page 77 - CITS - WCS - Mechanical

WORKSHOP SCIENCE - CITS

Solution
Mass of motor vehicle= 1200 kg
K.E. of the vehicle at 36 km/hr speed

1 1 2
x 1200 x 36 J KE= mv J
= mv 2 2 mv 2
2 2
v= 36km/hr =36 x = 10m/sec

K.E of the vehicle at 48 km/hr speed
1 2
mv
= x 1200 x 48 J ( 1kg.m/sec = 1N)
2
2
2
( 1Nm = 1J)
v= 48 km/hr =48 x= m/sec

1 2
mv
KE = x1200 x 10 x10=60000J
2
1 2
KE = mv x =106666.67 J
x1200 x
2
Increase in K.E of the vehicle = 106666.67 J - 60000J = 46666.67 J
= 46.666 KJ.
Workdone in vehicle operation
The Mechanical Work performed by the motor vehicle for its propulsion on road can generally be classified into
two major categories of work done.
- Workdone by the IC engine in developing full power under all condition of speed and load.
- Workdone by the motor vehicle in performing different operations on road like hill climbing/acceleration/braking/
towing and reversing operation.

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CITS : WCS - Mechanical - Exercise 5