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3 years ago

1. A certain atom has 20 electrons, 21 neutrons, and 20 protons. What is

Physics

1 answer:

Flauer [41]3 years ago

5 0

Answer:

Explanation:

An atom that contains 20 protons, 21 neutrons, and 20 electrons has an atomic mass of 41.

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3 years ago

Why we have leap year?

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Answer:February 29 is a date that usually occurs every four years, and is called leap day. This day is added to the calendar in leap years as a corrective measure, because the Earth does not orbit the sun in precisely 365 days.

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3 years ago

What is the speed of electromagnetic radiation in free speed

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4 years ago

Read 2 more answers

a 15kg television sits on a shelf at a height of 0.3 m how much gravitational potential energy is added to the television when i

DedPeter [7]

Answer:

<h2>103 Joules</h2>

Explanation:

In this problem we are required to find the potential energy possessed by the television

Given data

mass of television m = 15 kg

height added above the ground, h= 1-0.3 = 0.7 m

acceleration due to gravity g = 9.81 m/s^2

apply the formula for potential energy we have

P.E= m*g*h

P.E = 15*9.81*0.7 = 103 Joules

7 0

3 years ago

An object moving due to gravity can be described by the motion equation y=y0+v0t−12gt2, where t is time, y is the height at tha

LenaWriter [7]

Answer:

$t=6.4534 s$

Explanation:

This is an exercise where you need to use the concepts of free fall objects

Our knowable variables are initial high, initial velocity and the acceleration due to gravity:

$y_{0}=75m$

$v_{oy} =20m/s$

$g=9.8 m/s^{2}$

At the end of the motion, the rock hits the ground making the final high y=0m

$y=y_{o}+v_{oy}*t-\frac{1}{2}gt^{2}$

If we evaluate the equation:

$0=75m+(20m/s)t-\frac{1}{2}(9.8m/s^{2})t^{2}$

This is a classic form of Quadratic Formula, we can solve it using:

$t=\frac{-b ± \sqrt{b^{2}-4ac } }{2a}$

$a=-4.9\\b=20\\c=75$

$t=\frac{-(20) + \sqrt{(20)^{2}-4(-4.9)(75) } }{2(-4.9)}=-2.37s$

$t=\frac{-(20) - \sqrt{(20)^{2}-4(-4.9)(75) } }{2(-4.9)}=6.4534s$

Since the time can not be negative, the reasonable answer is

$t=6.4534s$

8 0

3 years ago