Question 5 of 10

A rock thrown vertically upward from the surface of the moon at a velocity of 36m/sec reaches a height of s = 36t - 0.8 t^2 met

Verdich [7]

Answer:

a. The rock's velocity is $v(t)=36-1.6t \:{(m/s)}$ and the acceleration is $a(t)=-1.6 \:{(m/s^2)}$

b. It takes 22.5 seconds to reach the highest point.

c. The rock goes up to 405 m.

d. It reach half its maximum height when time is 6.59 s or 38.41 s.

e. The rock is aloft for 45 seconds.

Step-by-step explanation:

Velocity is defined as the rate of change of position or the rate of displacement. $v(t)=\frac{ds}{dt}$
Acceleration is defined as the rate of change of velocity. $a(t)=\frac{dv}{dt}$

a.

The rock's velocity is the derivative of the height function $s(t) = 36t - 0.8 t^2$

$v(t)=\frac{d}{dt}(36t - 0.8 t^2) \\\\\mathrm{Apply\:the\:Sum/Difference\:Rule}:\quad \left(f\pm g\right)'=f\:'\pm g'\\\\v(t)=\frac{d}{dt}\left(36t\right)-\frac{d}{dt}\left(0.8t^2\right)\\\\v(t)=36-1.6t$

The rock's acceleration is the derivative of the velocity function $v(t)=36-1.6t$

$a(t)=\frac{d}{dt}(36-1.6t)\\\\a(t)=-1.6$

b. The rock will reach its highest point when the velocity becomes zero.

$v(t)=36-1.6t=0\\36\cdot \:10-1.6t\cdot \:10=0\cdot \:10\\360-16t=0\\360-16t-360=0-360\\-16t=-360\\t=\frac{45}{2}=22.5$

It takes 22.5 seconds to reach the highest point.

c. The rock reach its highest point when t = 22.5 s

Thus

$s(22.5) = 36(22.5) - 0.8 (22.5)^2\\s(22.5) =405$

So the rock goes up to 405 m.

d. The maximum height is 405 m. So the half of its maximum height = $\frac{405}{2} =202.5 \:m$

To find the time it reach half its maximum height, we need to solve

$36t - 0.8 t^2=202.5\\36t\cdot \:10-0.8t^2\cdot \:10=202.5\cdot \:10\\360t-8t^2=2025\\360t-8t^2-2025=2025-2025\\-8t^2+360t-2025=0$

For a quadratic equation of the form $ax^2+bx+c=0$ the solutions are

$x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$\mathrm{For\:}\quad a=-8,\:b=360,\:c=-2025:\\\\t=\frac{-360+\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2-\sqrt{2}\right)}{4}\approx 6.59\\\\t=\frac{-360-\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2+\sqrt{2}\right)}{4}\approx 38.41$

It reach half its maximum height when time is 6.59 s or 38.41 s.

e. It is aloft until s(t) = 0 again

$36t - 0.8 t^2=0\\\\\mathrm{Factor\:}36t-0.8t^2\rightarrow -t\left(0.8t-36\right)\\\\\mathrm{The\:solutions\:to\:the\:quadratic\:equation\:are:}\\\\t=0,\:t=45$

The rock is aloft for 45 seconds.

5 0

3 years ago

HELLLP ASAP FIRST PERSON WITH CORRECT ANSWER WILL RECEIVE BRAINLIEST

Nikitich [7]

Rotating Q 180 degrees using the center P has the same effect as reflecting Q over the Line M
Step-by-step explanation:
Rotating Q 180 degrees using the center P has the same effect as reflecting Q over the Line M and this is because Lines L and M are perpendicular lines ( i.e. lines that meet a right angle ( 90° ).
Hence rotating Q 180 degrees form the center will be similar to reflecting Q over any of the perpendicular lines

3 0

3 years ago

Combine the like terms to create an equivalent expression<br>what is <br>2 x - x + 8

Novay_Z [31]

Answer:

x + 8

Step-by-step explanation:

when theres just an x or any number there it is the same as 1x

2x - 1x = 1x / x

1x + 8 aka x + 8

7 0

2 years ago

Identify the number as real, complex, pure imaginary, or nonreal complex. (More than one of these descriptions may apply.) -9i

Agata [3.3K]

Answer:

Step-by-step explanation:

Me no hablas Inglish sorry pal

8 0

2 years ago

Anyone know what this means?

fgiga [73]

Answer:

It's an angle bisector and it was found using a compass

Step-by-step explanation:

First you use the compass to make a marking in the angle

Then you move the compass to the D and make another marking after that you move the compass to E (Make sure to use the same compass setting) and make a marking that intersects with the marking of D which creates F. Last you use a straight edge to make the angle bisector of ABC. (Sorry if you don't understand this it was difficult for me to explain)

4 0

2 years ago