A student determined Young's Modulus of elasticity using the formula Y = M g L 3 4 bd 3 δ . The…

A student determined Young's Modulus of elasticity using the formula Y=MgL34bd3δ. The value of g is taken to be 9.8 m s-2 without any significant error, his observations are as following.

Physical Quantity

Least count of the Equipment used for measurement

Observed Value
Mass (M) 1 g 2 kg
Length of bar (L) 1 mm 1 m
Breadth of bar (b) 0.1 mm 4 cm
Thickness of bar  (d) 0.01 mm 0.4 cm
Depression (δ) 0.01 mm 5 mm

Then the fractional error in the measurement of Y is :

  1. 0.155
  2. 0.0083
  3. 0.083
  4. 0.0155

Solution

Y=MgL34bd3δ

YY=MM+3l1+bb+3dd+δδYY=0.0005+3×0.001+0.0025+3×0.0025+0.002=0.0155

Asked in: JEE Main 2021 (01 Sep Shift 2)

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