After three half-lives, what fraction of a radioactive sample has decayed

5/6

1/2

7/8

2/3

a. Convert 21.0 cm to inches. Show your dimensional analysis setup. b. Convert 29.7 cm to inches. Show your dimensional analysis setup. c. State the dimensions, in inches, of the international standard for a letter-sized piece of paper. d.

A rock thrown with speed 12.0 m/s and launch angle 30.0 ∘ (above the horizontal) travels a horizontal distance of d = 15.5 m before hitting the ground. from what height was the rock thrown? use the value g = 9.800 m/s2 for the free-fall acceleration.

How do I calculate the orbital period of Mercury?

Imagine a Carnot engine has a hot reservoir of 680 K and a cold reservoir of 220 K. What is the efficiency of the engine?

In a mixture of the gases oxygen and helium, which statement is valid: (a) the helium molecules will be moving faster than the oxygen molecules, on average; (b) both kinds of molecules will be moving at the same speed;

A linearly-polarized electromagnetic (EM) wave has an electric field with amplitude 1000 V/m. You hold a a linear polarizer in front of it and rotate the polarizer so that all of the EM wave is blocked. You then rotate the polarizer 30 degree.

Let y'=4 x. find all values of r such that y = rx^{2} satisfies the differential equation. if there is more than one correct answer, enter your answers as a comma separated list.

What are the starting materials for nuclear fission

Why is it possible to throw a 0.145 kg baseball much further than a 7 kg bowling ball?

What is the name of the force that opposes or slows down the motion of objects