Answer:
a) 
b)
º
c) 
Explanation:
From the exercise we know that the collision between Daniel and Rebecca is elastic which means they do not stick together
So, If we analyze the collision we got

To simplify the problem, lets name D for Daniel and R for Rebecca
a) 
Since Daniel's initial velocity is 0



Now, lets analyze the movement in the vertical direction

Since 


Now, we can find the magnitude of Daniel's velocity after de collision

b) To know whats the direction of Daniel's velocity we need to solve the arctan of the angle
º
c) The change in the total kinetic energy is:
ΔK=
ΔK=![\frac{1}{2}[(45kg)(8m/s)^2+(70kg)(7.32m/s)^2-(45kg)(14m/s)^2]=-1094.62J](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7D%5B%2845kg%29%288m%2Fs%29%5E2%2B%2870kg%29%287.32m%2Fs%29%5E2-%2845kg%29%2814m%2Fs%29%5E2%5D%3D-1094.62J)
That means that the kinetic energy decreases
The two factors that increase the size of a population are natality, which is the number of individuals that are added to the population over a period of time due to reproduction, and immigration, which is the migration of an individual into a place.
Answer:695.5 N
Explanation:
mass of child 
Length of chain 
Tension in each chain 
(a)Tension at bottom point 
At lowest Point





(b)Force exerted by Seat will be Equal to Normal reaction




Answer:
This is due to the frequency
Explanation:
All sounds are characterized by the frequency range they have, the frequency is the number of times a sound wave is repeated in an instant of time called period.
To better understand this concept, an image is attached in which you can see the different types of waves according to their frequency. We can see that the audible frequencies are within the range of 10^3 to 10^8 [Hz].
Outside this range sounds are imperceptible to the human ear, which is why we cannot hear sounds emitted by physical or similar phenomena. It should be noted that as the frequency of the sound wave increases, the audible capacity of the human ear decreases.
Answer:
The answer is A. c is the letter that represents the speed of light