Get Answers to all your Questions

header-bg qa

Starting from rest, a fan takes five seconds to attain the maximum speed of 300\; rpm. Assume constant acceleration, then the time (in seconds) taken by the fan attaining half the maximum speed -

 

Option: 1 2

Option: 2 2.5

Option: 3 3

Option: 4 3.5

Answers (1)

best_answer

 

 

The maximum angular velocity is given by,  \omega =\frac{2\pi N}{60}

                                                              

                                           \Rightarrow \omega _{max}=\frac{2\pi \times 300}{60}=\frac{220}{7}rad/sec^{2}

Now,     \alpha =\frac{w_{f}-w_{i}}{\Delta t}

                \alpha =\frac{\omega _{f}-\omega _{i}}{\Delta t}=\frac{\frac{220}{7}-0}{5}=\frac{44}{7}rad/sec^{2}

Now, for half of  \omega_{max}

                \frac{\omega _{max}}{2}=0+\frac{44}{7}.t

                    \frac{100}{2}=\frac{44}{7}.t

                    t=2.5seconds

                

 

Posted by

Ajit Kumar Dubey

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE