To solve this problem it is necessary to apply the concepts related to momentum, momentum and Force. Mathematically the Impulse can be described as

Where,

F= Force

t= time

At the same time the moment can be described as a function of mass and velocity, that is

Where,

m = mass

v = Velocity

From equilibrium the impulse is equal to the momentum, therefore

PART A) Since the body ends at rest, we have the final speed is zero, so the momentum would be

Therefore the magnitude of the person's impulse is 1125Kg.m/s

PART B) From the equation obtained previously we have that the Force would be:

Therefore the magnitude of the average force the airbag exerts on the person is 45000N

-0 m/s

- average velocity=displacement/time

- the runners displacement is zero so her average velocity must be zero

**Answer:**

B) waves speed up

C) waves bend away from the normal

**Explanation:**

The index of refraction of a material is the ratio between the speed of light in a vacuum and the speed of light in that medium:

where

c is the speed of light in a vacuum

v is the speed of light in the medium

We can re-arrange this equation as:

So from this we already see that if the index of refraction is lower, the speed of light in the medium will be higher, so one correct option is

B) waves speed up

Moreover, when light enters a medium bends according to Snell's Law:

where

are the index of refraction of the 1st and 2nd medium

are the angles made by the incident ray and refracted ray with the normal to the interface

We can rewrite the equation as

So we see that if the index of refraction of the second medium is lower (), then the ratio is larger than 1, so the angle of refraction is larger than the angle of incidence:

This means that the wave will bend away from the normal. So the other correct option is

C) waves bend away from the normal