A stone ties to a rope is rotated in a vertical circle with uniform speed. If the difference between the maximum and minimum tension in the rope is $20\ N$, mass of the stone in $kg$ is:

& ;($\displaystyle g=10{ ms }^{ -2 }$)

Two springs have their force constant as $k_1$ and $k_2( k_1 > k_2)$& ;When they are stretched by the same force 

নিচের লেখচিত্রটিতে একটি স্প্রিং-এ প্রযুক্ত বলের সাথে দৈর্ঘ্য বৃদ্ধির পরিবর্তন দেখানো হয়েছে। 

স্প্রিংটির দৈর্ঘ্য বৃদ্ধি 3cm হলে স্প্রিং-এ সঞ্চিত শক্তির পরিমাণ কত ?

A simple pendulum has a string of length $l$ and bob of mass $m$. When the bob is at its lower position, it is given the maximum horizontal speed necessary for it to move in a circular path about the point of suspension. The tension in the string at the lowest position of the bob is

A spring of spring constant $5\times {10}^{3}N/m$ is stretched initially by $5cm$ from unstretched position. Then the work required to stretch is further by another $5cm$ is then