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A rectangular playground is 24 meters wide and has the same area as another rectangular playground that is 64 meters long and 48 meters wide. What is the perimeter of the first playground?
Area of the second playground: $64 \times 48 = 3072$ square meters.
The first playground has width 24 m and the same area:
$24 \times \text{length} = 3072$
$\text{length} = \dfrac{3072}{24} = 128$ meters.
Perimeter $= 2(24 + 128) = 2 \times 152 = \mathbf{304}$ meters.
Cooperative (Co-op) Advertising is a system in which two parties with a shared interest in selling a product jointly fund advertising campaigns. The textbook example is: a soft-drink manufacturer and a local grocery store split the cost of advertising the manufacturer's soft drinks. Both parties benefit: the manufacturer gains brand exposure and sales, while the store gains foot traffic and sales revenue. This model is especially beneficial for small business owners who could not afford to advertise on their own โ they leverage the manufacturer's resources to reach a wider audience. Cooperative advertising is a formal industry practice: manufacturers often provide co-op funds (typically a percentage of a retailer's purchases) that can be used for agreed advertising activities. It must be carefully distinguished from comparative advertising (comparing one brand to competitors) and institutional advertising (promoting corporate image rather than specific products).
Using the Relativistic Doppler Effect formula for an approaching source:
$f' = f \sqrt{\frac{1 + v/c}{1 - v/c}}$
Given $v = 0.5c$:
$f' = 10 \sqrt{\frac{1 + 0.5}{1 - 0.5}} = 10 \sqrt{\frac{1.5}{0.5}} = 10 \sqrt{3} \approx 10 \times 1.732 = 17.32 \text{ GHz}$.
Today: P + Q + R = 60 (since average = 20).
Therefore R = 60 โ 40 = 20 years today.
After 10 years: R = 20 + 10 = 30 years.
Two capacitors $C_1$ and $C_2$ are charged to 120 V and 200 V respectively. When connected together, the potential on each becomes zero. Which relation holds?
For the potential to become zero after connection, the total charge must be zero (charges cancel). Taking signs into account:
$Q_1 - Q_2 = 0 \Rightarrow C_1 \times 120 = C_2 \times 200$
$\frac{C_1}{C_2} = \frac{200}{120} = \frac{5}{3}$
$\Rightarrow 3C_1 = 5C_2$
The capacitors must have been charged with opposite polarities so that when connected, charges cancel. Conservation of charge gives $120C_1 = 200C_2$, yielding $3C_1 = 5C_2$.
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