# Do Clocks A and B Show the Same Time After 72 Hours Despite Speed Differences?

• Benjamin_harsh
In summary, the conversation discusses two clocks, A and B, that run either 5 minutes fast or 5 minutes slow per hour. After 12 hours, clock A will show 1 hour later than it should, while clock B will show 1 hour earlier. The conversation also mentions that both clocks have 12-hour displays.
Benjamin_harsh
Homework Statement
At 3:00 pm, clock was showing regular time. There are two clocks, one gains 5 min per hour. Another one loses 5 mins per hour. After how many hours both clocks will show the same time again?
Relevant Equations
My friend showed me:
Each hour clock A runs 5 minutes fast, after 12 hours, clock A is indicating 1 hour later than it should be. Although it is 3, it shows 4.

Similarly, because each hour clock B runs 5 minutes slow, after 12 hours, clock B is indicating 1 hour earlier than it should be. Although it is 3, it shows 2.

At t = 0h: Clock A points to 3. Clock B points to 3.
At t = 12h: Clock A points to 4. Clock B points to 2.
At t = 24h: Clock A points to 5. Clock B points to 1.
At t = 36h: Clock A points to 6. Clock B points to 12.
At t = 48h: Clock A points to 7. Clock B points to 11.
At t = 60h: Clock A points to 8. Clock B points to 10.
At t = 72h: Clock A points to 9. Clock B points to 9.

Another friend says: The times (after 72 hours) wouldn't match, as one would be 9 pm and the other 9 am.

Benjamin_harsh said:
Another friend says: The times (after 72 hours) wouldn't match, as one would be 9 pm and the other 9 am.
Does the question specifiy whether the clocks have 12-hour or 24-hour displays?

SammyS
PeroK said:
Does the question specifiy whether the clocks have 12-hour or 24-hour displays?
Clocks have 12-hour. Not 24 hours.

Benjamin_harsh said:
Clocks have 12-hour. Not 24 hours.

You can set my alarm clock for 7am. And it doesn't go off at 7pm as well!

PeroK said:
You can set my alarm clock for 7am. And it doesn't go off at 7pm as well!
How does it answer my question?

Benjamin_harsh said:
How does it answer my question?

Are you saying the clocks in the problem have 12-hour displays?

## 1. How do I determine the time difference between a fast and slow clock?

The easiest way to determine the time difference between a fast and slow clock is to compare the time shown on both clocks at the same time. Note the difference and use that to calculate the time difference between the two clocks.

## 2. Can I adjust the speed of a clock to match another clock?

No, it is not possible to adjust the speed of a clock. The speed of a clock is determined by its mechanism and cannot be manually changed.

## 3. Is there a formula for solving a fast and slow clock problem?

Yes, the formula for solving a fast and slow clock problem is: Time difference = (Fast clock time - Slow clock time) / (Fast clock speed - Slow clock speed).

## 4. What if the fast and slow clock have different units of time?

If the fast and slow clock have different units of time, you will need to convert them to the same unit before using the formula to solve the problem. For example, if one clock is in hours and the other is in minutes, you will need to convert the hours to minutes or vice versa.

## 5. Can I use the same formula for any fast and slow clock problem?

Yes, the same formula can be used for any fast and slow clock problem as long as the clocks have a constant speed and the time difference is within the same time frame. However, if the clocks have varying speeds or the time difference is over a long period, a different formula may be needed.

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