In a particle accelerator, protons are fired at a stationary ...

[jilianpiloj]

In a particle accelerator, protons are fired at a stationary target and collide elastically with the nuclei of the atoms in the target. In one such experiment, a beam of protons is fired with a speed of 2.10  107 m/s.
 
  The protons that undergo a collision rebound with a speed of 1.68  107 m/s. What is the mass of the nuclei that the protons are colliding against? A) 6.00 proton masses
  B) 7.00 proton masses
  C) 8.00 proton masses
  D) 9.00 proton masses
  E) 10.0 proton masses

Question 2

You drop a stone down a well that is 9.50 m deep. How long is it before you hear the splash? The speed of sound in air is 343 m/s.
 
  A) 1.39 s
  B) 1.40 s
  C) 1.41 s
  D) 1.42 s
  E) 1.43 s

[ryhom]

Answer to Question 1

D

Answer to Question 2

D

[jilianpiloj]

Thanks for the timely response, appreciate it

[kusterl]

Great answer, keep it coming