Question

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13 and 14​

Answer 1

13) Mass of engine = 8000kg

Mass of each wagon = 2000kg

Although this info has nothing to do with the question,

Anyways,

The force exerted by the engine = 40000N

Frictional force = 5000N

Net accelerating force = 40000N -5000N = (option3) 35000N

14) Mass = 25g = 0.025kg

Displacement = 7.5cm = 0.075m

We know,

Work = Force × displacement

Also,

work = change in kinetic energy,

Work = ½mv²

=> ½×0.025×(50²-40²)

=>½×0.025×900

=>11.25J

Now,

Putting this value in

Work = Force×Displacement

11.25 = Force × 0.075

Force = 11.25/0.075 = 150N

Average force exerted is (option 1) 150N

Cheers!

Answer 2

Answer:

[14 ]

Applyng work-energy theorem

W=Chang in kinetic energy

- f x s = 1/2 m ( v² - u²) by substituting

- f x 0.075 = 1/2 (0.025) ( 40² - 50²) solve for f

f = 150 N .