Ball bearings are made by letting spherical drops of molten metal fall inside a tall tower—called a shot tower—and solidify as they fall. (a) If a bearing needs 4.0 s to solidify enough for impact, how high must the tower be?

Video transcript

Hey everyone welcome back in this problem. The silicon oil droplet motion is investigated during a free fall experiment. A spherical shape droplet is established at the end of a syringes needle tip. The droplet released without initial speed, hits the ground after 0.85 seconds. And we're asked to determine the distance separating the tip from the ground. Alright, so let's just write out the information we're given. We know that the initial speed or velocity V not is going to be zero meters per second. Okay. We were given that in the problem. It was released without initial speed. We don't know the final speed. We know that the acceleration will be the acceleration due to gravity, which is going to be negative 9.8 m per second squared OK, assuming that we take the upward direction as positive. The time that it takes is 0.85 seconds. And we're asked the distance that it travels. Okay? That delta why? So we have three values that we know. We have one that we want to find. We can use our um equations. So we're going to choose the um equation without VF in it. Because we don't have information about V. F. And that's not what we're trying to find. And we're going to have that delta Y is equal to v naught t plus one half 80 squared. So Delta Y is going to be equal to zero plus one half times negative 9.8 m/s squared Times 0.85 seconds. All squared. This is gonna give us a delta y of negative 3.540-5 m. What the negative indicates is that this is going downward. Okay, the change in the Y position is negative, so this has gone downwards, which makes sense because that droplet is falling and so the distance is going to be the magnitude of that, which is going to be 3.54 m. We look at our answer choices. We see that this corresponds with answer choice b. 3.5 m separating the tip from the ground. Thanks everyone for watching. I hope this video helped see you in the next one.