6. A girl pushes her little brother on his sled with a force of 300 N for 750 m. a. How much work is this?
b. How much energy is used?
c. How much power does she use if it takes her 25s?
d. How much power does she use if she runs and complete the 750m in 10s?

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.