JEE Main 2021 — Laws Of Motion Question with Solution
From: JEE Main 2021 (Online) 20th July Morning Shift
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/s2. 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/s2 and s = 0.2]
This question includes a diagram. The text above accompanies the figure.
Choose an option
Show full solutionCorrect option: A
Correct answer
A686
Step-by-step explanation
The force equation in vertical direction is
Mg R = Ma
where,
M = collective mass of block and all three iron cylinders = 10 + 3 20 = 70 kg
a = acceleration of block = 0.2 ms2
g = 10 ms2 and s = 0.2
and R = normal reaction
Force along vertical axis Mg R = Ma
70g R = 70 0.2
R = 70 10 14
= 700 14 = 686 N
Mg R = Ma
where,
M = collective mass of block and all three iron cylinders = 10 + 3 20 = 70 kg
a = acceleration of block = 0.2 ms2
g = 10 ms2 and s = 0.2
and R = normal reaction
Force along vertical axis Mg R = Ma
70g R = 70 0.2
R = 70 10 14
= 700 14 = 686 N
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