Question

A nut is screwed onto a bolt with 12 turns per cm and diameter 1.18 cm. The blot is lying in horizontal direction. The nut spins at 216 r.p.m. Time taken by the nut to cover 1.5 cm along the bolt is

• A. 2s
• B. 3 s
• C. 4 s
• D. 5 s

Answer 1

Answer: (D)

5 s

Answer 2

Here, number of revolutions to cover 1.5 cm ‘n’ = $\frac { 1.5 } { 1 / 12 }$

= 18

Angular speed = ω 2πv = 2π × (216/60) = 7.2 π rds^-1

But ω = $\frac { \theta } { \omega }$ or $\mathrm { t } = \frac { \theta } { \mathrm { t } } = \frac { 2 \pi \mathrm { n } } { \omega } = \frac { 2 \pi \times 18 } { 7.2 \pi } = 5 \mathrm {~s}$