Question

Car of mass 1000 kilograms starts from rest and accelerates to speed of 72 km/h in 20 s, it then moves with a constant velocity for 80 seconds and is brought to rest in next 10 seconds. what is the total distance travelled by the car in the entire journey?

Answer 1

Explanation:

Mass of the car m=1000 kg

Initial velocity of car v

1

=0

Final velocity of car v

2

=100km/h=100×

18

5

m/s=27.78m/s

Average power of car=change in kinetic energy per unit time=

t

2

1

mv

2

2

−

2

1

mv

1

2

,since v

1

=0

So,average power of car=

t

2

1

mv

2

2

=

5

2

1

×1000×27.78

2

=7.71×10

4

W