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A railway engine (mass 10^(4) kg) is mov...

A railway engine (mass `10^(4)` kg) is moving with a speed of 72 km/h. The force which should be applied to bring it to rest over a distance of 20m is

A

7200N

B

1000N

C

3600N

D

100000N

Text Solution

Verified by Experts

The correct Answer is:
D
`u= 72 km//h= (72xx1000)/(3600) = 20m//s and v=0`
Using `v^(2)=u^(2) +2as`, we get, `0= 20xx20 +2(-a)xx20`
`therefore 40a=400`
`therefore` Retardation `a=10m//s^(2)`
`therefore` Force `= ma= 10^(4) xx 10 = 10^(5)N= 1,00,000N`
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