Two masses $m _ { 1 } = 5 \mathrm {~kg}$ and $m _ { 2 } = 4.8 \mathrm {~kg}$ tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when lift free to move ( $\mathrm { g } = 9.8 \mathrm {~m} / \mathrm { s } ^ { 2 }$ )\\
(1) $0.2 \mathrm {~m} / \mathrm { s } ^ { 2 }$\\
(2) $9.8 \mathrm {~m} / \mathrm { s } ^ { 2 }$\\
(3) $5 \mathrm {~m} / \mathrm { s } ^ { 2 }$\\
(4) $4.8 \mathrm {~m} / \mathrm { s } ^ { 2 }$