Refer to Design B |
A boy is playing with brooch B. He makes revolution with it along its edge. How many complete revolutions must it take to cover 80 K mm ? |
A) 2
B) 3
C) 4
D) 5
Correct Answer: C
Solution :
Directions (iii-iv) We have, circumference of silver part = 44 mm \[\therefore \,\,\,2\pi r=44\] \[\Rightarrow \,\,\,\,r=\frac{44}{2\times \frac{22}{7}}=7\,\,mm\] \[\therefore \,\,\,\,R=r+3=7+3=10\,\,mm\] Required number of revolutions \[=\frac{Distance\text{ }covered}{Circumference}\] \[=\frac{80\pi }{2\pi R}=\frac{80\pi }{2\pi \times 10}=4\]You need to login to perform this action.
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