If your speed changes from 10 km/h to 6 km/h then
you have an acceleration.
Whether it's a positive or negative one completely depends
on which direction you decided to call the positive direction,
when you started considering your speed and its changes.
If you decided to call the direction in which you're traveling
the positive direction, then a decrease in your speed is a
negative acceleration.
But you could just as easily have said that you're traveling
in the negative direction. If you did that, then a decrease in
your speed would be a positive acceleration.
It's completely up to you, and how you define things.
At the center, when the bob is hanging straight down
<h3>Newtons first law state that if a body is in motion it will be in motion and if a body is in rest it will tend to be in rest. This phenomena is also called INERTIA. Example: We tend to fall sideways when a car turn suddenly</h3>
Nuclear fission is seperating an atom so product is b.
Energy is released during nuclear fussion. Mass is converted into energy because E=mc^2, this is the energy that is released