a car is driven at a very high constant speed v ,on a staigt road.this causes lift (L) to act on the car due to airflow.the force of friction (f) acting between the wheels and the road is

 

a-------zero since the car is moving with constan t velcity.

b------f=mu mg where m is mass and mu is coffi of static friction

c-----f=mu(mg-L) assuming wheel do not loose contact

d-----f=d where d is the resultant backward force on the car due to air drag and other contact forces.

 

explain withe reason

 

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