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tester [92]
3 years ago
11

An attacker at the base of a castle wall 3.80 m high throws a rock straight up with speed 9.00 m/s from a height of 1.70 m above

the ground. a) will the rock reach the top? b) if so what is its speed at the top? if not, what initial speed must it have to reach the top? c) find the change in speed of a rock thrown straight down from the top of the wall at an initial speed of 7.4 m/s and moving between the same two points.d) does the change in speed of the downward moving rock agree with the magnitude of the speed change of the rock moving upward between the same elevations? e) why does this agree or not agree.
Physics
1 answer:
blagie [28]3 years ago
8 0

Answer:

First of all the attack is gonna die because its 2020 who throws a rock up over a wall to kill someone(cavemen) and

it's gonna be ↓

explanation:

An attacker at the base of a castle wall 3.60 m high throws a rock straight up with speed 8.00 m/s from a height of 1.70 m above the ground.

(a) Will the rock reach the top of the wall?

(b) If so, what is its speed at the top? If not, what initial speed must it have to reach the top?

(c) Find the change in speed of a rock thrown straight down from the top of the wall at an initial speed of 8.00 m/s and moving between the same two points.

(d) Does the change in speed of the downward-moving rock agree with the magnitude of the speed change of the rock moving upward between the same elevations? Explain physically why it does or does not agree.

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A 0.49-kg cord is stretched between two supports, 7.8m apart. When one support is struck by a hammer, a transverse wave travels
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To solve this problem we will apply the laws of Mersenne. Mersenne's laws are laws describing the frequency of oscillation of a stretched string or monochord, useful in musical tuning and musical instrument construction. This law tells us that the velocity in a string is directly proportional to the root of the applied tension, and inversely proportional to the root of the linear density, that is,

v = \sqrt{\frac{T}{\mu}}

Here,

v = Velocity

\mu= Linear density (Mass per  unit length)

T = Tension

Rearranging to find the Period we have that

T = v^2 \mu

T = v^2 (\frac{m}{L})

As we know that speed is equivalent to displacement in a unit of time, we will have to

T = (\frac{L}{t}) ^2(\frac{m}{L})

T = (\frac{7.8}{0.83})^2 (\frac{0.49}{7.8})

T = 5.54N

Therefore the tension is 5.54N

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TRUE or FALSE: Most Electromagnetic waves are blocked by the atmosphere.<br> True<br> False
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Suppose you look at a detailed spectrum of visible light from some object. How can you decide whether it is an emission line spe
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By observing the color of lines in the spectrum.

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3 0
3 years ago
(a) Figure 1 shows a mas of 1200 kg hung by a massless cable supported by a counterweight of mass 900 kg. You may assume the gra
Effectus [21]

Answer:

1.43 m/s², 10,300 N

Explanation:

First things first is to draw a picture.  Fortunately, one was already provided.

Next, we need to draw a free body diagram for each mass.

The 1200 kg mass has two forces acting on it: tension pulling up and weight pulling down.

Similarly, the 900 kg mass has two forces acting on it: tension pulling up and weight pulling down.

Now we apply Newton's second law.  Let's start with the 1200 kg.  If we say that up is positive, then:

∑F = ma

T - W = M(-a)

T - Mg = -Ma

Notice that I made the acceleration negative.  That's because we know that the heavier mass will be accelerating down.

Now we apply Newton's second law to the 900 kg mass:

∑F = ma

T - W = ma

T - mg = ma

Now we have two equations and two unknowns (T and a).  Let's solve for the acceleration first.  To do that, let's subtract the two equations so we can eliminate T (if you prefer, you can also use substitution instead):

-mg − (-Mg) = ma − (-Ma)

-mg + Mg = ma + Ma

g (M - m) = a (M + m)

a = g (M - m) / (M + m)

Given that M = 1200 kg, m = 900 kg, and g = 10 m/s²:

a = 10 m/s² (1200 kg - 900 kg) / (1200 kg + 900 kg)

a = 10/7 m/s²

a ≈ 1.43 m/s²

Now let's find the tension by plugging our answer into either of the two equations.

T - mg = ma

T - (900 kg) (10 m/s²) = (900 kg) (10/7 m/s²)

T = 72000/7 N

T ≈ 10,300 N

I'm not sure what rounding rules you need to follow, but hopefully this helps.

3 0
3 years ago
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