Why are there two ways we can measure energy food (KJ or CAL), what is the reason for this and why? detailed, please

Step-by-step explanation:

KJ ( kilo Joule) , this is the unit of Energy. Usually for measuring common energy.

CAL (calorie), this is the unit of Heat Energy.

calories are usually used for those related to food or human activities.

the conversion value :

1 Joule = 0.24 Calorie

1 Calorie = 4.2 Joule

54 kilometers per hour

step-by-step explanation:

according to rules:

1 km = 1000 meter

which means that 1 meter = 1/1000 km

1 hour = 3600 second [ as 1 hour = 60 min = 60 *60 seconds ]

which means that 1 second = 1/3600 hour

therefore, 1 kilometer/hour =

thus to convert 15 meter per second to kilometer per hour, we multiply 15 to 3.6 kilometer/hour.

15 meter/second=   which is the required answer.