Question

One gear pulley rotates at a speed of 3 rev/sec another gear roates at 5 rev/sec. if both start together after how many seconds will they be together again?

Answer 1

Thank you for asking this question.

The options for this question are missing, here are the missing options:

a) 3 sec

b) 5 sec

c) 15 sec

d) 20 sec

The correct answer is Option C: 15

First of all we will take the LCM of 3 and 5.

3. 5

15.

5. 3

(3 rotates 3,6,9,12,15

5 rotates 5,10,15)

If there is any confusion please leave a comment below.

Answer 2

In a given pulley the speed of the  g ear  can be 3 rev /sec  and it can rotates the speed as 5 /sec.so both can starts together.

They both can be rotates equally.

3 can rotates as 3, 6, 9, 12, 15 and the 5 can rotates the 5, 10, 15 so the exact answer is 15.