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svetoff [14.1K]
3 years ago
7

An object is dropped from 42m tall building. How long does It take to reach the ground?

Physics
1 answer:
yKpoI14uk [10]3 years ago
4 0

Answer:

It takes <u>2.93 s</u> for the object to reach ground from the height of 42 m.

Explanation:

Given:

Displacement of the object is, d=-42\ m

As it is dropped, initial velocity of the object is, u=0

Acceleration of the object is equal to acceleration due to gravity and is equal to, a=g=-9.8\ m/s^2

Now, using Newton's equation of motion and plugging in the values, we get:

d=ut+\frac{1}{2}at^2\\-42=0+\frac{1}{2}(-9.8)t^2\\-42=-4.9t^2\\t^2=\frac{-42}{-4.9}\\t^2=8.571\\t=\sqrt{8.571}=2.93\ s

So, it takes 2.93 s for the object to reach ground from the height of 42 m.

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Answer:

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Explanation:

Given that,

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For a standing wave, the distance between two consecutive nodes is equal to half of the wavelength.

\dfrac{\lambda}{2}=0.209\ m\\\\\lambda=0.418\ m

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f=\dfrac{2.57}{4.47}\\\\f=0.574\ Hz

Now we can find the velocity of the wave.

Velocity = frequency × wavelength

v = 0.574 × 0.418

v = 0.239 m/s

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3 years ago
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To solve this exercise it is necessary to apply the concepts related to Robert Boyle's law where:

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andrew11 [14]

Answer:

distance between the dime and the mirror, u = 0.30 m

Given:

Radius of curvature, r = 0.40 m

magnification, m = - 2 (since,inverted image)

Solution:

Focal length is half the radius of curvature, f = \frac{r}{2}

f = \frac{0.40}{2} = 0.20 m

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A train travels 90 kilometers in 2 hours, and then 66 kilometers in 2 hours. What is its average speed?
Inessa05 [86]
90+66=156
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