JEE Main 2021 (Online) 25th July Morning Shift | Properties of Matter Question 143 | Physics

Two wires of same length and radius are joined end to end and loaded. The Young's modulii of the materials of the two wires are Y₁ and Y₂. The combination behaves as a single wire then its Young's modulus is :

$$Y = {{2{Y_1}{Y_2}} \over {3({Y_1} + {Y_2})}}$$

$$Y = {{2{Y_1}{Y_2}} \over {{Y_1} + {Y_2}}}$$

$$Y = {{{Y_1}{Y_2}} \over {2({Y_1} + {Y_2})}}$$

$$Y = {{{Y_1}{Y_2}} \over {{Y_1} + {Y_2}}}$$

JEE Main 2021 (Online) 20th July Evening Shift

MCQ (Single Correct Answer)

-1

The length of a metal wire is l₁, when the tension in it is T₁ and is l₂ when the tension is T₂. The natural length of the wire is :

$$\sqrt {{l_1}{l_2}} $$

$${{{l_1}{T_2} - {l_2}{T_1}} \over {{T_2} - {T_1}}}$$

$${{{l_1}{T_2} + {l_2}{T_1}} \over {{T_2} + {T_1}}}$$

$${{{l_1} + {l_2}} \over 2}$$

JEE Main 2021 (Online) 20th July Evening Shift

MCQ (Single Correct Answer)

-1

Two small drops of mercury each of radius R coalesce to form a single large drop. The ratio of total surface energy before and after the change is :

$${2^{{1 \over 3}}}:1$$

$$1:{2^{{1 \over 3}}}$$

2 : 1

1 : 2

JEE Main 2021 (Online) 20th July Morning Shift

MCQ (Single Correct Answer)

-1

The value of tension in a long thin metal wire has been changed from T₁ to T₂. The lengths of the metal wire at two different values of tension T₁ and T₂ are l₁ and l₂ respectively. The actual length of the metal wire is :

$${{{l_1} + {l_2}} \over 2}$$

$$\sqrt {{T_1}{T_2}{l_1}{l_2}} $$

$${{{T_1}{l_2} - {T_2}{l_1}} \over {{T_1} - {T_2}}}$$

$${{{T_1}{l_1} - {T_2}{l_2}} \over {{T_1} - {T_2}}}$$

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