`1)`

`870km//h = 725/3 m//s`

`\vec{p} = m . \vec{v}`

`p = m . v`

`= 160 000 . 725/3 = 38666666 (kg.m//s)`

`.........`

`2)`

`m_1 = 1` tấn `= 1000 kg`

`v_1 = 60 km//h = 50/3 m//s`

`m_2 = 2` tấn `= 2000 kg`

`v_2 = 10 m//s`

`\vec{p} = m . \vec{v}`

`p_1 = m_1 . v_1`

`= 1000 . 50/3 = 50000/3 (kg.m//s)`

`p_2 = m_2 . v_2`

`= 2000 . 10 = 20000 (kg.m//s)`

`(p_1)/(p_2) = 50000/3 : 20000 = 5/6`

`............`

`v^2 = v_0^2 + 2as`

`= 0 + 2 . 1 . 50 = 100 => v = sqrt100 = 10 m//s`

`p = m . v = 1000 . 10 = 10000 (kg.m//s)`