Question

Which expression correctly describes energy using SI units? A. 1 J=1kg•m^2/s^2 B. 1 J= 1kg•m/s^2 C. 1 J= 1kg• m/s D. 1 J= 1kg•m^2/s

Answer 1

A. 1 J= 1 kg•m²/s²

Step-by-step explanation:

Energy is defined as the ability to work. The unit of energy is Joules. Work is said to be done if a force applied to an object cause the object to move through a distance.

Work = Force × Distance

Since force = mass × acceleration

Work = mass × acceleration × distance

Using the unit of each quantity to get the unit of work which is Joules

SI Unit of mass is kilogram (kg)

SI Unit of acceleration is metre per second square (m/s²)

SI Unit of distance is meters(m)

SI unit of work = kg × m/s² × m

SI unit of work = kgm²/s²

Hence 1J is also equivalent to 1kgm²/s²