Cannot solve Problems related to a Clock

In summary, the conversation discusses the dimensions of a clock and its hands, as well as the time shown on the clock. The individual is having trouble finding the central angle of the clock and solving for the velocity and acceleration of the hour hand at a given time. They also mention using the law of sines or cosines to solve for the missing information in an oblique triangle.
  • #1
ConfusedPhysics
2
0
"A clock has an hour hand that is 15.0 cm long, a minute hand that is 20.0 cm long, a secondhand that is 25.0 cm long."
"The time is 3 h 27 min 49 s"
"the hands are moving clockwise"
"for the hour hand calculate
1. speed of the hand
2. velocity of the hand at the given time"
"presume the hand from the the 12 position and find the change in
3. velocity,
4. average velocity,
5. average acceleration,
6. displacement"

The thing i am having the most trouble with is finding the central angle for the clock.

if i change time time into hours, it equals to 3.46 hours


if I multiply it by 30 to find the angle since each hour is 30 degrees to 12 o'clock it equals to 103.9 degrees.
but if i create a triangle using that number and the radius of the hour hand it will look like
this.
but this triangle does not make any sense since if solve for any of the other angles it will equal to
x= tan-1 (15/15)
x=45 degree
but that will make the angle equal to over 180 degrees, so i am confused on what i am supposed to do.1. The speed of the hour hand is the distance it goes divided by the time so
2*pi*r /(60*60)=v
v=7.6x10^-3 cm/s

2. the velocity of the given time is the magnitude of the speed so it is the same number but the i can't find the angle
V=7.6x10^-3 [some angle]

3. ∆v=(vf-vi)

∆v=(7.6x10^-3)^2+(-7.6x10^-3)^2-2(7.6x10^-3)(-7.6x10^-3)cos103.9
∆v=8.8x10^-5 cm/s

Its mostly the angle on what i am confused about
 
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  • #2
ConfusedPhysics said:
"A clock has an hour hand that is 15.0 cm long, a minute hand that is 20.0 cm long, a secondhand that is 25.0 cm long."
"The time is 3 h 27 min 49 s"

The thing i am having the most trouble with is finding the central angle for the clock.

if i change time time into hours, it equals to 3.46 hours

When the clock is at 3:00:00 exactly, the hands will appear like this: L

When the time is 3:27:49, I don't think the clock hands make the triangle as shown in your attachment.

if I multiply it by 30 to find the angle since each hour is 30 degrees to 12 o'clock it equals to 103.9 degrees.
but if i create a triangle using that number and the radius of the hour hand it will look like
this.
but this triangle does not make any sense since if solve for any of the other angles it will equal to
x= tan-1 (15/15)
x=45 degree
but that will make the angle equal to over 180 degrees, so i am confused on what i am supposed to do.

I'm not sure what you are doing here, but you can't treat this triangle like it was a right triangle. You have an oblique triangle, so you've got to use the law of sines or the law of cosines to figure out the missing information about the triangle.
 
  • #3
Thank you so much, I completely forgot about that. I found the angles and the answers to the problem
 
Last edited:

Related to Cannot solve Problems related to a Clock

1. Why is it important to be able to solve problems related to a clock?

Being able to solve problems related to a clock is important because it allows us to effectively manage our time and stay organized. It also helps us understand concepts such as time zones and calculating elapsed time.

2. What are some common problems that people encounter when dealing with clocks?

Some common problems people encounter when dealing with clocks include incorrect time settings, malfunctioning clock mechanisms, and difficulty reading analog clocks.

3. How can I improve my ability to solve problems related to a clock?

One way to improve your ability to solve clock-related problems is to practice regularly. This can involve setting and resetting the time on different types of clocks, solving time-based math problems, and learning about different clock mechanisms.

4. What are some resources I can use to learn more about solving clock-related problems?

There are many resources available online and in books that can help you improve your problem-solving skills when it comes to clocks. These can include tutorials, practice problems, and guides on how to troubleshoot common clock issues.

5. Are there any common mistakes people make when trying to solve problems related to a clock?

One common mistake people make when solving clock-related problems is not understanding the difference between 12-hour and 24-hour time formats. Another mistake is not paying attention to daylight saving time changes, which can affect the accuracy of the clock's time.

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