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Which two states border Washington, DC? Maryland, West Virginia Delaware, Virginia Delaware, West Virginia Maryland, Virginia

fredd [130]

Answer:

I believe it would be Pennsylvania and New Jersey they both border Maryland. Didn't see any other states that border Maryland with West Virginia and Virginia being exempt from the question.

Explanation:

5 0

3 years ago

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Your name is Galileo Galilei and you toss a weight upward at 20 feet per second from the top of the Leaning Tower of Pisa (heigh

Veseljchak [2.6K]

Answer:

a) v(t) = -32.2 ft/s² · t + 20 ft/s

b) h(t) = 184 ft + 20 ft/s · t - 16.1 ft/s² · t²

c) The weight will reach its maximum height after 0.62 s. The maximum height will be 190 feet.

Explanation:

Hi there!

a) Since the only force that acts on the weight is the gravity force, the object is under a constant downward acceleration g = -32.2 ft/s² (it is negative because we consider the upward direction as positive). The acceleration is the variation of the velocity over time (dv/dt). Then:

dv/dt = g

Separating variables:

dv = g dt

Integrating from the initial velocity, v0, to v and from t = 0 to t, we obtain:

v - v0 = g t

v = g t + v0

Then:

v(t) = -32.2 ft/s² · t + 20 ft/s

b) The velocity of the weight is the variation of the height over time:

dh/dt = v(t)

dh/dt = g t + v0

Separating varibles:

dh = g t dt + v0 dt

Integrating from initial height, h0, to h and from t = 0 to t:

h - h0 = 1/2 · g · t² + v0 · t

h = h0 + v0 · t + 1/2 · g · t²

Then:

h(t) = 184 ft + 20 ft/s · t - 1/2 · 32.2 ft/s² · t²

h(t) = 184 ft + 20 ft/s · t - 16.1 ft/s² · t²

c) When the weight reaches its maximum height, its velocity will be zero. Then, using the equation of velocity we can obtain the time at which the weight is at the maximum height:

v(t) = -32.2 ft/s² · t + 20 ft/s

0 = -32.2 ft/s² · t + 20 ft/s

-20 ft/s/ -32.2 ft/s² = t

t = 0.62 s

The weight will reach its maximum height after 0.62 s.

The maximum height will be h(0.62 s):

h(t) = 184 ft + 20 ft/s · t - 16.1 ft/s² · t²

h(0.62 s) = 184 ft + 20 ft/s · (0.62 s) - 16.1 ft/s² · (0.62 s)²

h(0.62 s) = 190 ft

The maximum height will be 190 feet.

3 0

3 years ago

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4. A 70.0 kg boy and a 45.0 kg girl use an elastic rope while engaged in a tug-of-war on an icy,

marta [7]

Answer:

$a_1 = 1.446m/s^2$

Explanation:

Given

$m_1 = 70.0kg$ -- Mass of the boy

$m_2 = 45.0kg$ -- Mass of the girl

$a_2 = 2.25m/s^2$ -- Acceleration of the girl towards the boy

Required

Determine the acceleration of the boy towards the girl ( $a_1$ )

From the question, we understand that the surface is frictionless. This implies that the system is internal and the relationship between the given and required parameters is:

$m_1 * a_1 = m_2 * a_2$

Substitute values for $m_1, m_2$ and $a_2$

$70.0 * a_1 = 45.0 * 2.25$

Make $a_1$ the subject

$\frac{70.0 * a_1}{70.0} = \frac{45.0 * 2.25}{70.0}$

$a_1 = \frac{45.0 * 2.25}{70.0}$

$a_1 = \frac{101.25}{70.0}$

$a_1 = 1.446m/s^2$

<em>Hence, the acceleration of the boy towards the girl is 1.446m/s^2</em>

7 0

3 years ago

If an object is thrown upward with an initial velocity of 128 ft/second, then its height after t seconds is given by the follow

IrinaK [193]

Answer:

The maximum height attained by the object and the number of seconds are 128 ft and 4 sec.

Explanation:

Given that,

Initial velocity u= 128 ft/sec

Equation of height

$h = 128t-32t^2$ ....(I)

(a). We need to calculate the maximum height

Firstly we need to calculate the time

$\dfrac{dh}{dt}=0$

From equation (I)

$\dfrac{dh}{dt}=128-64t$

$128-64t=0$

$t=\dfrac{128}{64}$

$t=2\ sec$

Now, for maximum height

Put the value of t in equation (I)

$h =128\times2-32\times4$

$h=128\ ft$

(b). The number of seconds it takes the object to hit the ground.

We know that, when the object reaches ground the height becomes zero

$128t-32t^2=0$

$t(128-32t)=0$

$128=32t$

$t=4\ sec$

Hence, The maximum height attained by the object and the number of seconds are 128 ft and 4 sec.

3 0

3 years ago

According to the pressure-flow hypothesis, why must sieve-tube elements in phloem be living cells?

Zigmanuir [339]

Base from the pressure-flow hypothesis, the sieve tube in the phloem should be living cells because sugars are transported across the membranes by the active transport which needs ATP that is produced during respiration. Hope this helps.

3 0

4 years ago