Physics Answers

The orbital period of Planet A is 16 years and its average distance to Star B is

5.25 a.u. Another planet called Planet C has an average distance of 10.3 a.u.

from Star B, using Kepler’s Third Law of Planetary Motion, compute the orbital

period of Planet C to Star B in days.

The moon has a mass of 7.34 x 10²²kg and a radius of 1.74 x 10⁶ meters. If you have a mass of 66kg, how strong is the force between you and the moon?

A motorcycle begins driving from at rest position. It accelerates at 8 km/hr2 for 20 seconds, then travels at a steady speed for another 20 seconds, all in the same direction. How much distance has it covered since it started driving?

How long will it take a 4.5Ci sample of material to reach an activity level of 0.14Ci if the half-life is 435 years?

A current of 0.2A passes through a 1.4kΩ resistor. What is the voltage across it?

How long would it take 4.0 x 10²⁰ atoms to decay to 1.0 x 10¹⁹ atoms if their half-life was 14.7 years?

A radioactive substance with a half-life of 3.0 days has an initial activity of 0.24Ci. What is its activity after 6.0 days?

A radioactive sample has a half-life of 10 min. What fraction of the sample is left after 40 min.

If a 4.0x10¹⁸ atoms decay with a life of 2.3 years, how many are remaining after 3.7 years?

Find the energy of incident photons if a 430-nm violet light is incident on a calcium photoelectrode with a work function of 2.71 eV.