You throw a 5.5 g coin straight down at 4.0 m/s from a 35-m-high bridge. (b) What is the speed of the coin just as it hits the water?

Video transcript

Hi, everyone in this practice problem. We're being asked to calculate the speed of a ball at the time of the ball landing onto the ground. We will have a ball with a mass of 200 g turned vertically off a cliff with a height of 15 m at a speed of 15 m per second. We're being asked to ignore a resistance and we're being asked to find the speed of the ball at the time of the landing on the ground. The options given are a 12.5 m per second. B 34.7 m per second. C negative 34.7 m per second and D negative 12.5 m per second. So we will consider the ball as a particle. And we have the following data from the problem statement at which the initial velocity V I actually equals to negative 15.0 m per second. And the negative sign here is coming from the fact that it is thrown vertically downwards off a cliff to the ground. So the downward displacement or delta Y is also given to be the height of the cliff itself which is zero m minus 50 m. So the total will be negative 50 m and the gravitational acceleration G is going to be 9.81 m per second square. Or in this case, the acceleration is going to equal to negative G or equals to negative 9.81 m per second squared. So we want to apply the kinematic equation which is going to be V F squared equals to V I squared plus to a delta Y. And we actually have all the information needed for us to calculate what V F squared is. So in this case, V F squared will then be V I squared, which is negative 15.0 m per second squared plus two A A is going to be negative 9.81 m per second squared. And delta Y is going to be negative 50 m just like. So that will give us the V F squared value of 12 oh five m squared per second squared. And taking the square root of that, we can find V F which is going to be the square root of 12 oh five m squared per second squared. And it will give us P F of 34.7 m per second. So the speed of the ball at the time of the landing on the ground is actually going to be 34.7 m per second, which is going to be free F and they all correspond to option B in our answer choices. So option B is going to be the correct answer to this particular practice problem. So if you guys still have any sort of confusion on this one, please make sure to check out our ado lesson videos on similar topics and that'll be it for this video. Thank you.