+2 votes
in Physics by kratos

A 11.7 ft wide ditch with the approach roads at an angle of 15° with the horizontal. With what minimum speed should a motorbike be moving on the road so that it safely crosses the ditch?

Ans.........

1 Answer

+5 votes
by kratos
 
Best answer

The center of mass of motor bike is C and it is in the shown position just before it is supposed to have taken ***. C' is the position when the bike lands safely ie., the rear part B must land on the road on the other side.

CC' is the range for the flight of the bike. CC' = R

               = 11.7' + 2.5' cos 15° + 2.5' Cos 15° = 16.53'  

We assume that the angle of projection of center of mass is 15°.

*Range for a two dimensional projectile : R = u² Sin 2Ф / g = u² Sin (215°) / g

      u = √(2 R g ) = √(2*16.53 * 9.8 / 0.3048) = 32.6 feet / sec**  

We do not consider some other factors like rotation about center of mass, friction etc. while answering this question.

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