1
JEE Main 2021 (Online) 20th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
For a certain radioactive process the graph between In R and t(sec) is obtained as shown in the figure. Then the value of half life for the unknown radioactive material is approximately :
JEE Main 2021 (Online) 20th July Evening Shift Physics - Atoms and Nuclei Question 118 English
A
9.15 sec
B
6.93 sec
C
2.62 sec
D
4.62 sec
2
JEE Main 2021 (Online) 20th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a binary star system of star A and star B with masses mA and mB revolving in a circular orbit of radii rA an rB, respectively. If TA and TB are the time period of star A and star B, respectively,

Then :
A
$${{{T_A}} \over {{T_B}}} = {\left( {{{{r_A}} \over {{r_B}}}} \right)^{{3 \over 2}}}$$
B
$${T_A} = {T_B}$$
C
$${T_A} > {T_B}$$ (if $${m_A} > {m_B}$$)
D
$${T_A} > {T_B}$$ (if $${r_A} > {r_B}$$)
3
JEE Main 2021 (Online) 20th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
At an angle of 30$$^\circ$$ to the magnetic meridian, the apparent dip is 45$$^\circ$$. Find the true dip :
A
$${\tan ^{ - 1}}\sqrt 3 $$
B
$${\tan ^{ - 1}}{1 \over {\sqrt 3 }}$$
C
$${\tan ^{ - 1}}{2 \over {\sqrt 3 }}$$
D
$${\tan ^{ - 1}}{{\sqrt 3 } \over 2}$$
4
JEE Main 2021 (Online) 20th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A body at rest is moved along a horizontal straight line by a machine delivering a constant power. The distance moved by the body in time 't' is proportional to :
A
$${t^{{3 \over 2}}}$$
B
$${t^{{1 \over 2}}}$$
C
$${t^{{1 \over 4}}}$$
D
$${t^{{3 \over 4}}}$$
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