Question

How many joules are in $148$ calories?

Answer 1

We can simply have calories into joules with the help of some basic conversions:
$1\text{ }calorie\text{ }=\text{ }1000\text{ }calories$
$1\text{ }kJ\text{ }=\text{ }1000\text{ }joules$
$1\text{ }kilocalories\text{ }\left( kcal \right)\text{ }=\text{ }4.184\text{ }kJ\text{ }\left( kJ \right)$
$1\text{ }calories\text{ }=\text{ }4.182\text{ }joule/calories$
Calories are the S.I. unit of energy.
1 calorie is required energy needed to make $1\text{ }gm$ of water rise by $1{}^\circ$
According to International Units the Energy should expressed in unit Joules

Complete answer:
In order to convert to $148$ calories into joules we already know that
$1\text{ }calories\text{ }=\text{ }4.182\text{ }joule/calories\text{ }approx$
Therefore, $148\text{ }calories\text{ }\times \text{ }4.182\text{ }joule/calories\text{ }=\text{ }618.936\text{ }Joules$

Additional Information: Also Calories are units of energy or we can say that the heat variously defines. The calorie was originally defined as amount of heat require at a pressure of $1$ standard atm to raise temperature of $1$ gram of water $1{}^\circ C$ From the year $1925$ this unit calorie has been defined in terms of the joule as international unit, the definition since year $1948$ is being that the one calorie is equal to approx. $4.2$joule and because of the quantity of the heat represented by calorie is known to differ at different temperatures to around $1$ percentage.

Note: Remember that the calories is counted for dietary reasons and that they are in fact kilocalories with the kilo in the prefix omitted in the usual scientific notations a capitalized notation Calorie is used here. In other words, if an apple is listed as having $90$ Calories, this straightforward indicates that the apple has actually $90,000$ calories.