The region where warm and cold air masses meet

A ball is thrown vertically upward from the top of a building 80 feet tall with an initial velocity of 64 feet per second. The d

-BARSIC- [3]

Answer:

a) $t=6.37s$

b) $t=3.3333s$

Explanation:

The knowable variables are the initial hight and initial velocity

$s_{o}=80ft$

$v_{os}=64ft/s$

The equation that describes the motion of the ball is:

$s=80+64t-16t^{2}$

If we want to know the time that takes the ball to hit the ground, we need to calculate it by doing s=0 that is the final hight.

$0=80+64t-12t^{2}$

a) Solving for t, we are going to have two answers

$t=\frac{-b±\sqrt{b^{2}-4ac } }{2a}$

a=-16

b=64

c=80

$t=-1.045 s$ or $t=6.378s$

<em><u>Since time can not be negative the answer is t=6.378s </u></em>

b) To find the time that takes the ball to pass the top of the building on its way down, we must find how much does it move too

First of all, we need to find the maximum hight and how much time does it take to reach it:

$v_{y}=v_{o}+gt$

at maximum point the velocity is 0

$0=64-32.2t$

Solving for t

$t=1.9875 s$

Now, we must know how much distance does it take to reach maximum point

$s=0+64t-16t^{2} =64(1.9875)-12(1.9875)^{2} =80ft$

So, the ball pass the top of the building on its way down at 160 ft

$160=80+64t-16t^{2}$

Solving for t

$t=2s$ or $t=3.333s$

Since the time that the ball reaches maximum point is almost t=2s that answer can not be possible, so the answer is t=3.333s for the ball to go up and down, passing the top of the building

4 0

3 years ago

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Three balls are kicked from the ground level at some angles above horizontal with different initial speeds. All three balls reac

astra-53 [7]

Answer:

They all hit at the same time

Explanation:

Let the time of flight is T.

The maximum height is H and the horizontal range is R.

The formula for the time of flight is

$T=\frac{2uSin\theta }{g}$ ..... (1)

Te formula for the maximum height is

$H=\frac{u^{2}Sin^{2}\theta }{2g}$ .... (2)

From equation (1) and (2), we get

$\frac{T^{2}}{H}=\frac{\frac{4u^{2}Sin^{2}\theta }{g^{2}}}{\frac{u^{2}Sin^{2}\theta }{2g}}$

$\frac{T^{2}}{H}=\frac{8}{g}$

$T=\sqrt{\frac{8H}{g}}$

here, we observe that the time of flight depends on the maximum height and according to the question, the maximum height for all the three balls is same so the time of flight of all the three balls is also same.

8 0

3 years ago

A loop circuit has a resistance of R1 and a current of 1.8 A. The current is reduced to 1.6 A when an additional 3.8 Ω resistor

Allisa [31]

Answer:

Value of $R_1=30.4ohm$

Explanation:

We have given

In first case resistance is $R_1$ and current is 1.8 A

Let the potential difference is v

So $1.8=\frac{v}{R_1}$ ----eqn 1

In second case resistance is $R_1+3.8$ and current is 1.6 A and potential difference will be as it is a series connection

So $1.6=\frac{v}{R+3.8}$ ----eqn 2

From eqn 1 and eqn 2

$1.8R_1=1.6R_1+6.08$

$R_1=30.4ohm$

6 0

3 years ago

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Ground-based radio telescopes can collect data from distant objects in space

Butoxors [25]

Answer:

A. during the day or night and in any weather conditions.

Explanation:

Ground-based radio telescopes can be used to collect data from distant objects in space during the day or night in any weather condition.

They do not depend or are they affected by weather and they pass well through them.

Telescopes are devices used to obtain information about distant bodies usually astronomical in nature.
Optical telescopes use the visible range of light and they are overwhelmed by the sun during the day.
Bad weather conditions can also diminish the reception of light.
They work best at night.
Radio telescopes uses electromagnetic radiations and can work at any time and during any weather.

6 0

3 years ago

A jet aircraft with a mass of 4,475 kg has an engine that exerts a force (thrust) equal to 60,800 N. (a) What is the jet's accel

BartSMP [9]

Answer:

a) 13.59 m/s²

b) 67.95 m/s

c) 169.875 m

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity