A truck weighing 1000kgf changes its speed from 36km/h to 72 km/h in 2 minutes.Calculate:1)The work done by engine and 2) it's power (Take g = 10 m/sec2
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1)Mass m=1000kg
initial velocity u=36km/h=36x1000/60x60=10m/s
final velocity v=72km/h=20m/s
Time t=2mins =2 x 60 =120sec.
workdone W=Force x displacement
W=F.S
W=ma.S........................1)
Using Newton Law of Motion
v²-u²=2aS
(20)²-(10)²=2aS
400-100=2aS
aS=300/2
aS=150m²/s²
putting the value of aS in equation 1,we have
W=2000 x 150
W=300,000 joules
2)power P =work done /time taken
P=300,000/120sec.
p=2500 joules/sec.
initial velocity u=36km/h=36x1000/60x60=10m/s
final velocity v=72km/h=20m/s
Time t=2mins =2 x 60 =120sec.
workdone W=Force x displacement
W=F.S
W=ma.S........................1)
Using Newton Law of Motion
v²-u²=2aS
(20)²-(10)²=2aS
400-100=2aS
aS=300/2
aS=150m²/s²
putting the value of aS in equation 1,we have
W=2000 x 150
W=300,000 joules
2)power P =work done /time taken
P=300,000/120sec.
p=2500 joules/sec.
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