Which is better... electric cars or gas cars. Explain.

electric cars

Explanation:

although electric cars are more expensive, you will save money on rhe gass bill because you won't need to pay for gas. they also make less harmful toxins for the earth

The time between the emission of the wave and it's reception was 0.4 seconds.

Explanation:

The sound wave emitted by the sonar traveled from the boat to the fishes and came back, therefore the distance of it's total route is twice the distance from the boat to the fishes. We can apply the average speed formula in order to solve this problem, this is done below:

We were given the distance traveled by the wave and it's speed, therefore we can solve for the time:

The time between the emission of the wave and it's reception was 0.4 seconds.