Question

An army truck of mass 8 tonnes has a resistance of 75 N/t. Find the power of the truck for moving with a constant speed of 45 km.p.h.

Answer 1

Answer:

7.5 KJ    

Explanation:

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Answer 2

The power of the truck is 7.5 KW

The mass of the truck is (m) = 8 tons

The resistance of the truck is = 75 N/t

∴ The resistance offered by the whole truck is = 75 × 8 N

                                                                             = 600 N

The speed of the truck (v) = 45 km.p.h

∴ In 1 hr the truck moves 45 km

⇒ In 3600 s the truck moves 45 km  [∵ 1 hr = 3600]

⇒ In 1 s the truck moves = (45/3600) × 1000 m

                                      = 12.5 m

∴ The power of the truck is (P) = F.v

⇒ P = 600 × 12.5 W

⇒ P = 7500 W

⇒ P = 7.5 KW

So, the power of the truck will be 7.5 KW.