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UNO [17]
3 years ago
7

A small rock is thrown vertically upward with a speed of 21.0 m/s from the edge of the roof of a 35.0-m-tall building. The rock

doesn't hit the building on its way back down and lands in the street below. Ignore air resistance.(a) What is the speed of the rock just before it hits the street?(b) How much time elapses from when the rock is thrown until it hits the street?
Physics
1 answer:
klasskru [66]3 years ago
6 0

Answer:

a) Vf = 33.78m/s

b) t = 5.478s

Explanation:

We can calculate final speed using:

Vf^{2}=Vo^{2}-2*g*\Delta Y

where Vo = 21m/s;  g = 10m/s2;   ΔY = -35m

Vf = 33.78m/s

Now, having final speed, we can calculate the amount of time elapsed:

Vf = Vo - g * t    where Vf = -33.78m/s;   Vo = 21m/s;   g = 10m/s2

t = 5.478s

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pishuonlain [190]

Answer:

True. Diffusion and osmosis are forms of passive transport.

Explanation:

In diffusion, particles move from an area of higher concentration to one of lower concentration until equilibrium is reached.

In osmosis, a semipermeable membrane is present, so only the solvent molecules are free to move to equalize concentration.

8 0
3 years ago
Read 2 more answers
A car travels 100 m while decelerating to 8 m/s in 5 s.<br> a) What was its initial speed?
viktelen [127]

Answer:

Vi = 32 [m/s]

Explanation:

In order to solve this problem we must use the following the two following kinematics equations.

v_{f} =v_{i} - (a*t)\\

The negative sign of the second term of the equation means that the velocity decreases, as indicated in the problem.

where:

Vf = final velocity = 8[m/s]

Vi = initial velocity [m/s]

a = acceleration = [m/s^2]

t = time = 5 [s]

Now replacing:

8 = Vi - 5*a

Vi = (8 + 5*a)

As we can see we have two unknowns the initial velocity and the acceleration, so we must use a second kinematics equation.

v_{f}^{2} = v_{i}^{2} - (2*a*d)

where:

d = distance = 100[m]

(8^2) = (8 + 5*a)^2 - (2*a*100)

64 = (64 + 80*a + 25*a^2) - 200*a

0 = 80*a - 200*a + 25*a^2

0 = - 120*a + 25*a^2

0 = 25*a(a - 4.8)

therefore:

a = 0 or a = 4.8 [m/s^2]

We choose the value of 4.8 as the acceleration value, since the zero value would not apply.

Returning to the first equation:

8 = Vi - (4.8*5)

Vi = 32 [m/s]

6 0
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klemol [59]

Answer:

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Explanation:

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Leona [35]

The correct match of each item to the clean water regulation it describes is as follows:

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<h3>What are the functions of clean water regulation?</h3>

Clean Water Act (CWA) is a regulatory body that establishes the basic structure for the regulation of pollutants discharge and maintenance of quality standards of the surface waters.

On the other hand, the Safe Drinking Water Act was founded to oversee the protection of the quality drinking water. The regulatory body is primarily concerned with potable water all waters, whether from above ground or underground sources.

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6 0
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Astar begins as a blank a large cloud of gas and dust
crimeas [40]
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