Hello There!
The law of conservation of mass states that <em>Matter/substances/energy can not be created or destroyed, it can only be transferred from state to state.</em>
Answer:
the angle of incidence equals the angle of reflection
Answer:
v = 0.028 m/s
Explanation:
In this case you take into account that all the elastic potential of the box, when the spring is compressed is equal to the kinetic energy of the box before it hits the spring. That is:
(1)
m: mass of the box = 4.5kg
k: spring constant = 85N/m
x: compression of the spring = 6.5cm = 0.0065m
You solve the equation (1) for v:
(2)
Next, you replace the values of the parameters:

The velocity of the box when it hits the spring is 0.028m/s
Use a very very very powerful microscope...
There are several approaches. The most favourable one (in my opinion) is this one:
1. Asking a question
2. Doing a research (how to answer this question)
3. Creating a hypothesis (NOT a thesis!)
4. Experimenting (to prove the hypothesis)
5. Analysing results from the experiment
6. Writing a thesis