Answer:
d = 100.8 ft
Explanation:
As we know that initial speed of the van is 40 miles then the stopping distance is given as 70 feet
here we know that

so here we have

now again if the speed is increased to 48 mph then let say the stopping distance is "d"
so we will have

now divide the above two equations


By law of refraction we know that image position and object positions are related to each other by following relation

here we know that



now by above formula


so apparent depth of the bottom is seen by the observer as h = 3.39 cm
Hi there!
We can use the work-energy theorem to solve.
Recall that:

The initial kinetic energy is 0 J because the crate begins from rest, so we can plug in the given values for mass and final velocity:

Now, we can define work:

Now, plug in the values:

Solve for theta:
