A vessel $1.4 \mathrm{m}$ wide and $2.0 \mathrm{m}$ long is filled to a depth of $0.8 \mathrm{m}$ with a liquid of mass density $840 \mathrm{kg} \mathrm{m}^{-3} .$ What will be the force in $\mathrm{N}$ on the bottom of the vessel $(a)$ when being accelerated vertically upwards at $4 \mathrm{m} \mathrm{s}^{-1},(b)$ when the acceleration ceases and the vessel continues to move at a constant velocity of $7 \mathrm{m} \mathrm{s}^{-1}$ vertically upwards?
$$[(a) 25985 \mathrm{N},(b) 18458 \mathrm{N}]$$