Vibrations and Waves Legacy Problem #1 Guided Solution
Problem*
Jerome and Claire are doing the Period of a Pendulum Lab. They observe that a pendulum makes exactly 10 complete back and forth cycles of motion in 21.8 seconds. Determine the period of the pendulum.
Audio Guided Solution
One problem which students have when solving waves problems is confusing the concept of period with the concept of frequency. Here we're asked to determine the period of a pendulum given that it makes 10 cycles in 21.8 seconds. Now when you're thinking about period, you have to think that it's the time per something that happened. Time divided by the number of things which happened. When you're solving for frequency, it's just the opposite. It's the number of things which happened per unit of time. So for period here, what we have to do is we have to divide the time by the number of things that happened. 21.8 divided by the 10 cycles will give us 2.18 seconds in the period.
Solution
2.18 s
Habbits of an Effective Problem Solver
- Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
- Identify the known and unknown quantities and record in an organized manner, often times they can be recorded on the diagram itself. Equate given values to the symbols used to represent the corresponding quantity (e.g., \(\descriptive{v}{v,velocity} = 12.8 \unit{\meter\per\second}\), \(\descriptive{λ}{λ,wave length} = 4.52 \unit{m}\), \(\descriptive{f}{f,frequency} = \colorbox{gray}{Unknown}\)).
- Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
- Identify the appropriate formula(s) to use.
- Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
Read About It!
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