Question

A steel block of 10 kg rests on a horizontal floor as shown. When three iron cylinders are placed on it as shown, the block and cylinders go down with an acceleration of 0.2 m/s². The normal reaction R' by the floor if the mass of the iron cylinders is equal and of 20 kg each, is ______.

[take g = 10 m/s² and µ_s = 0.2]

 

Options

• 714

• 716

• 684

• 686

Answer 1

A steel block of 10 kg rests on a horizontal floor as shown. When three iron cylinders are placed on it as shown, the block and cylinders go down with an acceleration of 0.2 m/s². The normal reaction R' by the floor if the mass of the iron cylinders is equal and of 20 kg each, is 686.

Explanation:

A steel block has a mass of 10 kg.

Mass of all cylinder M = 20 × 3 + 10 = 70 kg

In the vertical direction, the force equation,

Mg - N = Ma

70 × 10 - N = 70 × 0.2

N = 70[10 - 0.2] = 686 N