Mater doesn't just appear or disappeared. Chemical elements are still there just the connections and how it combines changes.
So what goes into your chemical eqation must still exist after the change.
Sound waves....................................
The approximate amount of thrust(force) you need to apply to the lander to
keep its velocity roughly constant is zero.
<h3>What is Newton's second law of motion?</h3>
Newton's second law of motion states that the acceleration the force acting
on the object is directly proportional to its rate of change of momentum.
F = m a
If the object is moving with uniform velocity, it simply means that the
acceleration is zero, and the corresponding force will also be zero.
Read more about Constant velocity here brainly.com/question/3052539
Radioactive "decay" means particles and stuff shoot OUT of a nucleus.
After that happens, there's less stuff in the nucleus than there was before.
So the new mass number is always less than the original mass number.