The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is :

A body, under the action of a force $$\overrightarrow F = 6\widehat i - 8\widehat j + 10\widehat k,$$ acquires an accelerations of 1 m/s². The mass of this body must be

Three forces acting on a body are shown in the figure. To have the resultant force only along the y-direction, the magnitude of the minimum additional force needed is

A roller coaster is designed such that riders experience ''weightlessness'' as they go round the top of a hill whose radius of curvature is 20 m. The speed of the car at the top of the hill is between