The spring inside a clicky pen is a perfect way to learn about projectile motion. Post Views: 319 News PREVIOUS ARTICLE Apple’s iMac Pro arrives December 14, starting at $4,999 NEXT ARTICLE Facebook bats back after a second former exec accuses it of negatively impacting society Related Post Bitcoin Is Soaring. Here’s Why It’s Not Ready for the Big Time / Dec 12 Meet the guy who gets beat up in all of Marvel’s Netflix superhero shows / Dec 13 The Refreshed Razer Blade Stealth Hones its Edge / Dec 13 Leave a Reply Click here to cancel reply. Name (required) Mail (required) (not be published) Website