If a football is thrown from rest with an acceleration of 8.5 m/s2, and had an final

Physics

1 answer:

AnnyKZ [126]2 years ago

4 0

Answer:

t = 2.94 seconds

Explanation:

Given that,

The initial velocity of the football, u = 0

The final velocity of the football, u = 25 m/s

Acceleration, a = 8.5 m/s²

We need to find the time for which the football is accelerating. Let the time is t. We know that,

$a=\dfrac{v-u}{t}\\\\t=\dfrac{v-u}{a}\\\\t=\dfrac{25-0}{8.5}\\\\t=2.94\ s$

So, the football is accelerating for 2.94 seconds.

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A string has its 4th harmonic at 31.5 Hz. What is the fundamental frequency?

seropon [69]

Given data

*The given 4th harmonic frequency is 31.5 Hz

The fundamental frequency is calculated as

$\begin{gathered} f_n=\frac{31.5}{4} \\ =7.875\text{ Hz} \end{gathered}$

Hence, the fundamental frequency is 7.875 Hz

5 0

1 year ago

Atom X contains seven protons and seven neutrons. atom Z contains seven protons and eight neutrons. which of the following state

stiks02 [169]

Answer:

The correct answer is option A: they are isotopes.

Explanation:

From atom X we know that the number of protons is 7 and the number of neutrons is 7 and from atom Z we know that the number of protons is 7 and the number of neutrons is 8.

Since the number of protons of atom X and atom Z is the same, we have that atom X and atom Z is the same element. The difference in the number of neutrons tells us that atom X and atom Z are isotopes. Remember that an isotope is one element that has atoms with different numbers of neutrons.

The mass number is given by:

$A = p + n$

Where <em>n</em> is the number of neutrons and <em>p </em>is the number of protons.

For atom X and atom Z we have:

$A_{x} = 7 + 7 = 14$

$A_{z} = 7 + 8 = 15$

Hence, they have a different mass number.

We know that the element with 7 protons is nitrogen. The first isotope is $^{14}_{7}N$ and the second isotope is $^{15}_{7}N$ . Both isotopes are stables (they are not radioactive).