Step 1: Young's modulus definition
\[ Y = \frac{{Stress}}{{Strain}} \]
Step 2: Effect of temperature increase: An increase in temperature causes an increase in strain. This leads to a reduction in Young’s modulus. Therefore, Young’s modulus decreases.
A particle is moving in a straight line. The variation of position $ x $ as a function of time $ t $ is given as:
$ x = t^3 - 6t^2 + 20t + 15 $.
The velocity of the body when its acceleration becomes zero is: