ROTATIONAL MECHANICSfor a rear wheel driven bicycle,indicate the direction of friction for the front and rear wheels(forward or backward)CONSIDER THAT THERE IS NO SLIDING ANY WHERECASE 1 :- WHEN THE REAL WHEEL BREAKES ARE APPLIEDCASE2 :- WHEN THE FRONT WHEEL BREAKS ARE APPLIEDCASE 3:- WHEN BOTH THE BREAKES ARE APPLIEDSIMULTANEOUSLYCASE 4:- WHEN THE PEDAL IS ACCELERATING IT

In all the above cases the friction acts in forward direction. In the three cases of application of breaks the breaks tries to stop bicycle by applying force in backward direction Hence friction acts in forward direction. And in the case of acceleration the tires pushes the earth in backward direction to move forward i.e. force is applied in backward direction and friction acts in forward direction. PLEASE LIKE MY ANSWER IF YOU ARE SATISFIED BY IT AND BEST OF LUCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

but the answer is 

case 1        frction will be back ward on rear wheel and forwanrd on front wheel

case 2       friction will be forward on rear wheel and backward on front wheel

case 3     friction will be back wards on both wheels

 case 4    friction will be forward on rear wheel and backward on front wheel