Question 138: Laws of Motion

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 0.2 m/s
2
. The normal reaction R' by the floor if mass of the iron cylinders are equal and of 20 kg each, is ____________ N. [Take g = 10 m/s
2
and $$\mu$$
s
= 0.2]

Accepted Answer

The force equation in vertical direction is
Mg $$-$$ R = Ma
where,
M = collective mass of block and all three iron cylinders = 10 + 3 $$	imes$$ 20 = 70 kg
a = acceleration of block = 0.2 ms
$$-$$2
g = 10 ms
$$-$$2
and $$\mu$$
s
= 0.2
and R = normal reaction
Force along vertical axis Mg $$-$$ R = Ma
$$	herefore$$ 70g $$-$$ R = 70 $$	imes$$ 0.2
$$\Rightarrow$$ R = 70 $$	imes$$ 10 $$-$$ 14
= 700 $$-$$ 14 = 686 N

Answer

686

Answer

684

Answer

714

Answer

716

Laws of Motion

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