# A car drives off a 25 m tall bridge travelling at a horizontal velocity of 25 m/s?

a) How far does it travel from the bridge?

b) How long is the car in the air?

Relevance

Let the car take t sec to fall 25m

=>By s = ut + 1/2gt^2

=>25 = 0 + 1/2 x 9.8 x t^2

=>t = √5.10

=>t = 2.26 sec -----------------Answer for (B)

Now let the car cover R meter horizontally in 2.26 sec

Thus by s = ut

=>R = 25 x 2.26

=>R = 56.47 m -----------------Answer for (A)

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• Why?  If I was travelling at 90 km/hr I would not attempt to drive off the side of a bridge.  Was the driver on the mobile phone?  Was another vehicle involved?  Many questions should be asked that are more important than where the car landed.

t= sqrt( 2 h / g) = 2.26 s  and distance = vt

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• y(t) = ½at² + v₀t  + y₀ is the basic formula you need to know.

Standard gravity is -9.80665 m/s²

This will find time of flight.

Then multiply by 25m/s for distance horizontal

• Ah but "standard gravity" only applies to one place and one time.  So one should not presume such accuracy unless it is actually specified.  It varies by more than this at different times of the tides.

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• Solve b first.

b) 0.5*9.81*t^2 = 25

a) s = 25*t

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