A job hunter was left baffled during an interview when hit with a puzzling brainteaser.
Despite racking their brains, they couldn’t crack the conundrum and have since reached out to social media users for assistance. The candidate, who was vying for a mechanical engineer role, did not anticipate such a perplexing query.
They shared: “During an interview was asked this brainteaser I couldn’t answer correctly, was wondering if anyone could help me out. You have two identical pucks that are slid across a frictionless surface at the same starting velocity.
“They have to cross a finish line at the same distance from the starting line. However, when puck A is slid, it slides across a ‘dip’ in the table, but returns to the original height after the dip.
“Puck B slides across a completely level surface. Which reaches the finish line first?” While some social media users argued both pucks would finish simultaneously, others speculated that puck A would be quicker.
One individual reasoned: “Both reach at the same time. Since the horizontal distance and initial velocities are the same, the time taken should be the same too – by the kinematic equation: distance (in x) equals velocity(in x) *time.”
Another user chimed in: “Make the dip a flat horizontal down, a flat level at the bottom, and then an equal, flat horizontal back up. the horizontal component of the movement has an acceleration and then a deceleration the cos of the angle.”
A third user explained: “From what I understand from my analysis and others on here (i was wrong at first). Puck A arrives first because it accelerates on the way down the dip, and on the way up can only decelerate back to initial velocity, due to the ‘rotational’ deceleration being the only change in its velocity.
“So essentially puck A is speeding up for a bit then going back to normal, like temporarily accelerating in a vehicle, which negates friction with energy input into the system.”