Question

what is the si unit for energy? a. speed b. pound c. joule d. calorie

Explanation:

• Option A: Speed is a physical quantity, not a unit.
• Option B: Pound is a unit of force in the imperial system, not an SI unit for energy.
• Option C: Joule (\(J\)) is the SI unit for energy. For example, the work done \(W = F\times d\) (force \(F\) in Newtons and distance \(d\) in meters) has units \(N\cdot m\), and \(1\ N\cdot m=1\ J\). Kinetic energy \(E_{k}=\frac{1}{2}mv^{2}\) (mass \(m\) in \(kg\) and velocity \(v\) in \(m/s\)) also has units in joules.
• Option D: Calorie is a non - SI unit of energy (\(1\ cal = 4.186\ J\)).

Answer:

C. Joule