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The driver of a three-wheeler moving wit...

The driver of a three-wheeler moving with a speed of `36 km//h` sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle ? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.

Text Solution

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We are given:
`u= 36 kmh^(-1)= 10ms^(-1), v= 0, t= 4s`
total mass= `400+ 65= 465kg`
We are to calculate: Average retarding force on the vehicle.
We know that,
v=u + at
`implies 0= 10 + 4a implies a = -2.5 m s^(-2)`
So, retarding force =` 465 xx 2.5=1162.5 N.`
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