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

A body of mass 1 kg is thrown upwards with a velocity 20 m/s. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction? (g = 10 m/s²)

An explosion blows a rock into three parts. Two parts go off at right angles to each other. These two are, 1 kg first part moving with a velocity of 12 m s^$$-$$1 and 2 kg second part moving with a velocity 8 m s^$$-$$1. If the third part flies off with a velocity of 4 m s^$$-$$1, its mass would be :