After 2 half-lives, what fraction of a radioactive substance remains? 1/4 1/2 1/3 1/8

Write an answer to the Guiding Question: As bread dough rises,why doesn't its mass increase?

Select the true statements. The distance across a galaxy group is usually a few hundred thousand light-years. Stars cluster together to form galaxy groups. Galaxy groups typically contain several hundred galaxies. Galaxy groups are mostly composed of empty space.

The variable you change on purpose in an experiment is called the independent variable . It is what you are testing to see how it affects the result. In this activity., what was that variable? The height you dropped the ball from The bounce height the ball reached The kind of graph you made C The number of times you collected data

The portion of the larger electromagnetic spectrum that humans can see is known as the __ visible spectrum Infrared spectrum microwave spectrum vestibular spectrum

The fate of the Universe depends upon the true nature of Dark Energy. True False

Radio waves travel at the speed of light,which is $3.00\times 10^{8}m/s$ How many kilometers will radio messages to outer space travel in exactly 35.1 days? $\square $

Problem 17 A tiger leaps horizontally from a 7.5-m-high rock with a speed of $3.0m/sec$ How far from the base of the rock will she land?

How are work and energy related? (Read the procedure section carefully). A Energy is the ability to do work, and work is the mean by which energy changes from one form to another. B Energy is work multiplied by time, and work is equal to power. C Energy is the ability to do work, and work is energy divided by time. D Energy is the ability to do work, and work is power divided by energy. E Energy is the ability to do work, and work is energy multiplied by time.

When you stand at rest on a pair of bathroom scales, the readings on the scales will always add up to equal your weight. each be half your weight. each equal your weight.

Which of the following did the geocentric model and Copernicus' heliocentric model have in common. The Moon orbited around the Sun but closer to the Earth than the planets. Mercury and Venus were between the Earth and the Sun. The orbits of the planets were perfect circles. The Earth was at the center of the universe.