A deuteron of mass M is moving at speed v before colliding with an immobile α-particle of mass 2M. The deuteron is deviated 90° from its initial direction. Knowing that the collision is elastic, determine the angle of the trajectory of the α-particle with respect to the deuteron’s initial path.

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron

Scientists follow specific processes in order to determine valid explanations and conclusions from observations. david observed strange lights in the sky above his home outside of roswell, new mexico. the only explanation that makes sense to him is that there are ufos in the area. what should david do next to verify his explanation?

Which of these has some mechanical energy? a. an atom b. heat inside earth c. a book on a shelf d. the fire from a lit match