Answer:

Explanation:
According to the law of conservation of energy, the total energy of the system can be expresed as the sum of the potential energy and kinetic energy:

When the spring is in its equilibrium position, that is
, the object speed its maximum. So, we have:

In order to double its maximum speed, that is
. We have:

The answer is A. Only an object in motion has kinetic energy.
Answer:
At the highest point the velocity is zero, the acceleration is directed downward.
Explanation:
This is a free-fall problem, in the case of something being thrown or dropped, the acceleration is equal to -gravity, so -9.80m/s^2. So, the acceleration is never 0 here.
I attached an image from my lecture today, I find it to be helpful. You can see that because of gravity the acceleration is pulled downwards.
At the highest point the velocity is 0, but it's changing direction and that's why there's still an acceleration there.
Answerana alyom kint gahda amshi
Explanation: