A plastic cube with side length 10cm and mass 0.70kg is held fully submerged in fresh water (density 1.0×103kgm−3) with its faces horizontal and then released from rest.
(a) Draw a clearly labeled free-body diagram for the cube at the instant just after it is released.
(b) Calculate the magnitude of the upward force exerted by the water on the cube.
(c) Determine both the magnitude and direction of the net force acting on the cube immediately after release, and hence calculate its initial acceleration.
(d) As the cube moves upward, describe qualitatively how the magnitude of the net force and the acceleration change before the cube reaches the water surface. Assume viscous drag is negligible.