Question

A ball of mass 0.25 kg attached to the ends of a string of length 1.96 m is rotating in a horizontal circle. The string will break, if tension is more than 25 N. What is the maximum velocity with which the ball can be rotated?

• A. 3 $ms^{ - 1}$
• B. 5 $ms^{ - 1}$
• C. 9 $ms^{ - 1}$
• D. 14 $ms^{ - 1}$

Answer 1

Answer: (D)

14 $ms^{ - 1}$

Answer 2

F = $\frac{ mv^2 }{ r }$
or $v^2 = \frac{ F r }{ m }$
$\therefore v^2 = \frac{ 25 \times 1.96 }{ 0.25 } = 196$
or $v = \sqrt{ 196 } = 14 \, ms^{ - 1}$