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Bingel [31]
3 years ago
7

A ball is released from a tower at a height of 100 meters toward the roof of another tower that is 25 meters high. The horizonta

l distance between the two towers is 20 meters. With what horizontal velocity should the ball be imparted so that it lands on the rooftop of the second building?
Physics
1 answer:
I am Lyosha [343]3 years ago
7 0
-- During the time the ball is flying from the high roof to the low roof,
it's going to fall (100-25) = 75 meters.
How long does it take an object dropped from rest to fall 75 meters ?

Distance = (1/2) · (gravity) · (time)²

75 m = (4.9 m/s²) · (time)²

Time² = (75 m) / (4.9 m/s²)
Time² = 15.31 sec²
Time = √(15.31 sec²)  =  3.91 seconds 

So the ball has to cover the horizontal distance of 20 meters 
in 3.91 seconds.

Distance = (speed) · (time)

20 m = (speed) · (3.91 sec)

Speed = (20 m) / (3.91 sec)

Speed  =  5.11 m/s
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Answer:

L=55.9m

Explanation:

The equation for the period of a simple pendulum is:

T=2\pi\sqrt{\frac{L}{g}}

In our case what we know is the period and the acceleration of gravity, and we need to know the length of the pendulum, so we can write:

L=(\frac{T}{2\pi})^2g

Which for our values is:

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6 0
3 years ago
What is inertia? explain please!
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3 0
3 years ago
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A red laser from the physics lab is marked as producing 632.8-nm light. When light from this laser falls on two closely spaced s
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Answer:

Explanation:

fringe separation or fringe width is directly proportional to wavelength .

Δ₁ / Δ₂ = wave length of first laser / wavelength of second laser

Δ₁ is fringe separation in first case and Δ₂ is fringe separation in second case.

putting the given values

632.8 / wavelength of second laser = 4.5 / 4.64

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3 0
3 years ago
The model of the atom has changed as scientists have gathered new evidence. Four models of the atom are shown below, but one imp
nexus9112 [7]

Answer: Dalton’s model

Explanation:

In the attached image we can see four atomic models labeled with four letters:

W represents the current and accepeted atomic model: a nucleus with an electron cloud, where the orbit and position of the electrons around the nucleus is defined by specific regions (associated with specific energy levels) where there is a greater probability of finding the electron at any given moment. It is important to note this model was improved by the works in quantum physics done by Louis de Broglie and Erwin Schrodinger.

X represents Rutherford's model (This model was proposed after Thomson's model). Ernest Rutherford conducted a series of experiments in order to corroborate Thomson's atomic model. However the results of the experiment led him to find out there is a concentration of charge in the atom's core (which was later called nucleus) surrounded by electrons.  This lead to a new atomic model, in which the atom has a positive charged nucleus surrounded by negative charged particles that move similar to the orbit of the planet around the Sun.

Y represents Thomson's model, also called  the <em>plum pudding</em> model. This scientific found out that atoms contain small subatomic particles with a negative charge (later called electrons). However, taking into consideration that at that time there was still no evidence of the atom nucleus, Thomson thought the electrons were immersed in the atom of positive charge that counteracted the negative charge of the electrons. Just like the raisins embedded in a pudding or bread.

Z represents Bohr's model. This model was proposed by the danish physicist Niels Bohr after Rutherford's model. In fact, this model was Rutherford's model with the following addition: electrons orbit the nucleus (like planets around the sun) in specific orbits at different energy levels around the nucleus.

So, the only missing model is <u>Dalton's model</u>, which was the first atomic model:  the atom represented as a solid, indestructible and indivisible mass. An idea that was already accepted by that time since the ancient Greeks.

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3 years ago
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