Answers:
a) 
b)
c) 
d) 
Explanation:
For this situation we will use the following equations:
(1)
(2)
Where:
is the <u>height of the model rocket at a given time</u>
is the i<u>nitial height </u>of the model rocket
is the<u> initial velocity</u> of the model rocket since it started from rest
is the <u>velocity of the rocket at a given height and time</u>
is the <u>time</u> it takes to the model rocket to reach a certain height
is the <u>constant acceleration</u> due gravity and the rocket's thrust
<h2>a) Time it takes for the rocket to reach the height=4.2 m</h2>
The average velocity of a body moving at a constant acceleration is:
(3)
For this rocket is:
(4)
Time is determined by:
(5)
(6)
Hence:
(7)
<h2>b) Magnitude of the rocket's acceleration</h2>
Using equation (1), with initial height and velocity equal to zero:
(8)
We will use
:
(9)
Finding
:
(10)
<h2>c) Height of the rocket 0.20 s after launch</h2>
Using again
but for
:
(11)
(12)
<h2>d) Speed of the rocket 0.20 s after launch</h2>
We will use equation (2) remembering the rocket startted from rest:
(13)
(14)
Finally:
(15)
Answer:
It ensures the doors seal properly when closed. This seal will fend off the elements, and prevent water from leaking inside the vehicle. It is further used on windows to seal and protect the windows.
Explanation:
Answer:
The moon moves because the earth rotates around its axis of rotation. Although the moon moves too around its orbit, the speed is too small to notice. In other words, the moon's position changes insignificantly, however, the earth rotates fast enough to notice.
To solve the problem it is necessary to apply the theory of sine waves. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by

Where,
v= velocity
f = frequency
Re-arrange to find v, we have

PART A ) Replacing with our values we have,


PART B) In the case of the period we know that it is defined as a function of frequency as,

That is to say that using the previously given values we have that the period in seconds is,

PART C) Finally the transverse wave velocity is given by,

Where,
T= Period
Linear mass density
Re-arrange to find 



Answer:
K = m g (h₀ - h_plat)
Explanation:
Let's use energy conservation to solve this problem, write the energy at two points of interest
Initial. Higher
E_initial = m g h₀
Final. Lower
E_end = K + Ep
E_end = ½ m v² + m g h_plat
Energy is conserved
E_initial = E_end
m g h₀ = K + m g h_plat
K = m g (h₀ - h_plat)