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
Answer:
10.87 m
Explanation:
Total length of the wire = 25 m
Let the length of one piece is y and other piece is 25 - y
Let the side of square is a.
So, 4 a = y
a = y / 4
And the side of triangle is b
3 b = (25 - y)
b = (25 - y) / 3
Area of square, A1 = side x side =
A1 = y² / 16
Area of equilateral triangle, A2 = 

Total area, A = A1 + A2

For maxima and minima, fins dA /dy

It is equal to zero.

9y = 173.2 -6.928 y
15.928 y = 173.2
y = 10.87 m
So, the length of wire to make square is 10.87 m.
Answer:
The initial speed of the ball is 23.3 m/s.
Explanation:
Given that,
Angle = 44°
Range = 55.7 m
We need to calculate the initial speed of the ball
Using formula of range

Where. u = initial velocity
r = range
g = acceleration due to gravity
Put the value into the formula




Hence, The initial speed of the ball is 23.3 m/s.
The answer is B. You divide 717 by the acceleration by gravity of earth (9.8 m/s) and divide 5320 by your answer.
Answer:
There is a gravitational force between the hand and the cup, but Earth's gravity is stronger, so Earth's gravity pulls the cup down.