Which unit is used to measure energy?

Which unit is used to measure energy?

• A. Pascal (Pa)
• B. Newton (N)
• C. Joule (J)
• D. Watt (W)

Answer: (C)

Energy is quantified in joules because a joule measures the amount of work or energy transferred. By definition, one joule is the energy transferred when a force of one newton moves an object one meter, so 1 J = 1 N·m and in base units 1 J = kg·m^2/s^2. This ties energy directly to the ability to do work, which depends on both force and distance. The other units refer to different quantities: a pascal is a unit of pressure (force per area), a newton is a unit of force, and a watt is a unit of power (energy per unit time). For instance, a 60-watt light bulb uses energy at 60 joules per second, so its energy use over a period is 60 times the number of seconds. Larger energy amounts are often expressed in kilojoules or calories, but the fundamental SI unit for energy is the joule.

Energy is quantified in joules because a joule measures the amount of work or energy transferred. By definition, one joule is the energy transferred when a force of one newton moves an object one meter, so 1 J = 1 N·m and in base units 1 J = kg·m^2/s^2. This ties energy directly to the ability to do work, which depends on both force and distance.

The other units refer to different quantities: a pascal is a unit of pressure (force per area), a newton is a unit of force, and a watt is a unit of power (energy per unit time). For instance, a 60-watt light bulb uses energy at 60 joules per second, so its energy use over a period is 60 times the number of seconds. Larger energy amounts are often expressed in kilojoules or calories, but the fundamental SI unit for energy is the joule.