# The driver of a 1250 kg car initially traveling at 11.1 m/s,?

The driver of a 1250 kg car, initially traveling at 11.1 m/s, applies the brakes, bringing the car to rest in a distance of 25.0 m.?

Find the network done on the car

### 4 Answers

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- Demiurge42Lv 71 month ago
KE = 1/2 m v^2

KE = 1/2*1250kg*(11.1m/s)^2 = 77,000 J

The net work done on the car is -77,000 J to 3 significant figures.

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- 1 month ago
for the car ; 0 - 11.1x11.1 = 2xa x 25

so that it’s retardation is a = -123.21/50 = -2.46 m/sec’2

then net work done W = m a s = 1250 x 2.46 x 25 = 76,785 J.

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- Anonymous1 month ago
Work = -KE = -1250/2*11.1^2 = -77.0 kjoule

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- billrussell42Lv 71 month ago
first, find de-acceleration to stop in that distance.

v² = v₀² + 2ad

0 = 11.1² + 2a25

a = –2.4642 m/s²

now find force needed

F = ma = 1250 x 2.4642 = 3080 N

work = Fd

W = 3080 x 25 = 77000 J

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