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Question

The formula for conversion between Fahrenheit and Celsius is

°F = X + (1⋅8 × °C)

What is factor X?

This question was previously asked in
NDA II 2019 GAT Previous Year Paper (17-Nov-2019)
The correct answer is

32

Understanding Temperature Conversion Formula

The question asks us to identify the factor X in the given formula for converting temperature from Celsius (°C) to Fahrenheit (°F). The formula provided is:

\(\) \text{°F} = \text{X} + (1.8 \times \text{°C}) \(\)

Standard Celsius to Fahrenheit Conversion

The standard and widely accepted formula for converting a temperature from the Celsius scale to the Fahrenheit scale is:

\(\) \text{°F} = \left(\frac{9}{5} \times \text{°C}\right) + 32 \(\)

We know that the fraction \(\frac{9}{5}\) is equal to the decimal value 1.8.

So, the standard formula can also be written as:

\(\) \text{°F} = (1.8 \times \text{°C}) + 32 \(\)

Identifying Factor X

Now, let's compare the given formula with the standard formula:

  • Given Formula: \(\) \text{°F} = \text{X} + (1.8 \times \text{°C}) \(\)
  • Standard Formula: \(\) \text{°F} = 32 + (1.8 \times \text{°C}) \(\) (rearranging the standard formula slightly to match the structure)

By comparing these two formulas, we can see that the structure is the same, and the coefficient for °C is 1.8 in both cases. The constant term that is added to the result of \((1.8 \times \text{°C})\) is X in the given formula and 32 in the standard formula.

Therefore, by direct comparison, the factor X must be equal to 32.

Comparing Options for Factor X

Let's look at the provided options:

  • Option 1: 32
  • Option 2: 22
  • Option 3: 98
  • Option 4: 42

Our derived value for factor X is 32, which matches Option 1.

Component Given Formula Standard Formula
Temperature in Fahrenheit (°F) °F °F
Temperature in Celsius (°C) °C °C
Multiplication Factor for °C 1.8 1.8 (from 9/5)
Added Constant X 32

This comparison confirms that X = 32.

Revision Table: Temperature Scales

Scale Symbol Freezing Point of Water Boiling Point of Water
Celsius °C 0°C 100°C
Fahrenheit °F 32°F 212°F
Kelvin K 273.15 K (approx) 373.15 K (approx)

Additional Information: Temperature Conversion Factors

Temperature conversion is a common operation in physics and everyday life. The relationship between different temperature scales is linear.

The formula \(\text{°F} = \left(\frac{9}{5} \times \text{°C}\right) + 32\) can be rearranged to convert Fahrenheit to Celsius:

\(\) \text{°F} - 32 = \frac{9}{5} \times \text{°C} \(\)

\(\) \text{°C} = \frac{5}{9} \times (\text{°F} - 32) \(\)

Conversions involving Kelvin (K) are also important. Kelvin is an absolute scale, meaning 0 K is absolute zero.

  • Celsius to Kelvin: \(\) \text{K} = \text{°C} + 273.15 \(\)
  • Kelvin to Celsius: \(\) \text{°C} = \text{K} - 273.15 \(\)

Fahrenheit to Kelvin conversions usually go via Celsius first.

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Important Questions from Temperature and heat

  1. At which temperature Celsius and Fahrenheit are equal?

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