Answer:
about 42.35 m/s
Explanation:
Use the equation for accelerated motion (g), and with zero initial velocity that doesn't include time:

which for our case would reduce to:

then the velocity just before hitting would be about 42.35 m/s
Sorry don’t know this one
The answer they are looking for is the last one. However the last two are technically correct but the third one would result in negative work.
Hello!
This is a matter of superposition.
When the waves peak at the same time and place, they produce constructive interference, meaning the waves interact together in a positive way, to make a wave with Amplitude of both waves added together. When the peaks differ however, at the same time and place, then it is destructive interference and the waves essentially cancel each other out.
Hope this helps. Any questions please just ask. Thank you kindly.