Answer:

Explanation:
Total internal reflection can happen when light goes from a medium with higher refractive index (in this case, glass) to a medium with lower refractive index (in this case, water).
Snell's Law tells us that
, where the <em>i</em> stands for incident (in this case, glass) and the <em>r</em> for refracted (in this case, water). We want to know when
, that is, when
, and this happens when the incident angle is:

Which for our values means:

Answer:
The acceleration of the crate is 
Explanation:
Recall the formula that relates force,mass and acceleration from newton's second law;

Then in our case, we know the force applied and we know the mass of the crate, so we can solve for the acceleration as shown below:

Answer:
Weight
Explanation:
Weight is the downward pull on an object due to gravity.
For example, the moon has less gravity than Earth so we would weigh less on the moon. Our Mass and volume always stay the same but our weight could change.
Answer:
Part a)
distance = 112 miles
Part b)
current position = 112 miles from the position of town
Explanation:
Part a)
Since the distance marker is showing the distance between the town and the position of john at all time
so here we have

Part b)
Current position of John is given as

from the position of the town