The radioactive element strontium-90 has a half-life of 28 years. suppose we start with a 50-g mass of strontium-90. how much will be left after 174 years? compute the answer to three significant digits.

The earth exerts a gravitational force of 500 n on amy. what is amy’s mass in kg?

Aball is thrown from the top of a building with an initial velocity of 21.9 m/s straight upward, at an initial height of 51.6 m above the ground. the ball just misses the edge of the roof on its way down, as shown in the figure. (a) determine the time needed for the ball to reach its maximum height. (b) determine the maximum height. (c) determine the time needed for the ball to return to the height from which it was thrown, and the velocity of the ball at that instant. (d) determine the time needed for the ball to reach the ground. (e) determine the velocity and position of the ball at t = 5.35 s.

If the specific heat of a metal is 0.850 j/g °c, what is its atomic weight?