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In a new unit system, 1 unit of time = 10 s, 1 unit of mass = 5 kg, and 1 unit of length = 20 m. How many joules is 1 unit of energy in this new system?

1. 10
2. 20
3. 50
4. 100

Correct answer: 20

Solution

Substituting the new units: 1 unit energy = 5 * 400 / 100 = 20 J.

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