When bicycle and motorcycle riders pop a wheelie, alarge acceleration causes the bikes front wheel to leavethe ground. Let M be the total mass of the bike-plus-ridersystem; let x and y be the horizontal and vertical distanceof this systems cm from the rear wheels point of contactwith the ground (Fig. 10-72). (a) Determine the horizontalacceleration a required to barely lift the bikes front wheeloff of the ground. (b) To minimize the accelerationnecessary to pop a wheelie, should x be made as small oras large as possible? How about y l How should a riderposition his or her body on the bike in order to achievethese optimal values for x and y l (c) If x = 35 cm andy = 95 cm, find a.FIGURE 10-72 101.
• System o Objectsinit o Forcesonitfromoutside(external) Fd Forceand Ability“todo Positivework Displacementare stuff”increases done parallel Fd Forceand Ability“todo Negativework Displacementare stuff”decreases done anti-parallel F Forceand Ability“todo Zeroworkdone Displacementare stuff”is d perpendicular uncharged W=±Fd Joules=Newtonsmeters (J)=(N)(m) Work=Forcedisplacement • ASystemHas: o Theobjectbeingdisplaced. o