Which unit is equivalent to J kg^-1? a) m s^-1 b) m s^-2 c) m^2 s^-1 d) m^2 s^-2

When working out unit equivalences the most straightforward approach is to use formulas (often in the data booklet) to help reach a correct answer. We start by looking at Joules; knowing a Joule is a unit of energy we can consult the data booklet and find that work done (an equivalent measure of energy) is equal to force * distance. Another commonly used formula is the formula for force: force = mass * acceleration. Now we can combine the two, leading to Joules = Mass * Acceleration * Distance. We know mass is measured in kg, acceleration is measured in m s^-2 and distance is measured in m. Given that the original unit is J kg^-1 we see that the kg's cancel out and we're left with m s^-2 * m = m^2 s^-2. Therefore the answer is D.