If there is no friction under either box, see figure 4.21, determine the acceler
ID: 440459 • Letter: I
Question
If there is no friction under either box, see figure 4.21, determine the acceleration of both blocks. Assume masses and P are known. Figure 4.21:Explanation / Answer
change in length of cord between mA n mB is 0 so : xA be distance travelled by mA xB be distance travelled by mB -4xA + 3xB = 0 => double differentiating with time -4aA + 3aB = 0 => aA = 3aB/4 -equation 1 force on mA : 4T ( T is tension in cord) towards right force on mB : P - 3T towards right 4T = mA*aA - equation 2 P-3T = mB*aB - equation 3 solving for aB T = mA*aA/4 from 2 T = mA*3*aB/16 from 1 p - 9mA*aB/16 = mB*aB aB(16mB+9mA)/16 = P => aB = 16P/(16mB+9mA) => aA = 12P/(16mB+9mA)