A Block of Mass M=4 $v _ { \mathrm { i } } = 9.2 \mathrm {~m} / \mathrm { s }$

Short Answer

A block of mass m=4.4 kg, moving on frictionless surface with a speed $v _ { \mathrm { i } } = 9.2 \mathrm {~m} / \mathrm { s }$ makes a sudden perfectly elastic collision with a second block of mass M , as shown in the figure. The second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of $v _ { \mathbf { f } } = 2.5 \mathrm {~m} / \mathrm { s }$ What is the mass M of the second block?