Answers for the problems in the book

Hi folks,

Just so you can make sure you're on the right track, here are the answers to the problems in the book.

Plug and Chug
1. 20 x 3.5 = 70J

3. First find work from question #2.
500N x 2.2m = 1100J
Then take 1100 J/2 = 550W

Think and Solve
2. Twice the power would be 1/2 the time. So the answer is 5 s.

4. So the car starts with 40,000,000 J. If the car is 25% fuel efficient that means that only 25% of that goes to making the car move so only 10,000,000 of the energy is used. So now, plug n chug.
10,000,000 = 1000 x D
10,000 m = D Or 10 Km