Solve each problem. Speed of a PlaneMary Lynn left by plane to vi...

Question

Solve each problem. Speed of a PlaneMary Lynn left by plane to visit her mother in Louisiana, 420 km away. Fifteen minutes later, her mother left to meet her at the airport. She drove the 20 km to the airport at 40 km per hr, arriving just as the plane taxied in. What was the speed of the plane?

Accepted Answer

Hello everyone in this video, we're going to be looking at this practice problem where we want to calculate the speed of a boat where Ryan was traveling to visit his uncle. And we need to determine that based off of the uncle speed as well. So we're given a couple of numbers. The first is that Ryan is km away And his uncle begins to travel to meet him at the ports 7.5 hours after Ryan has left the city and at a speed of 50 km/h, The uncle drove 25 km to the porch and the ship and Ryan's uncle arrive at the same time. So in order to calculate the speed of the boat, let's sort of think about this scenario. So I'm going to do this timeline and say that this starting point is when Ryan left the city. And if I continue all the way here, we're going to say this is Ryan arriving at the airport. Well, we know that when Ryan's ship arrived at the ports, his uncle also arrived at the ports. But we also know that Ryan's uncle left 7.5 hours after Ryan left the city, I'm just going to say that this point here is Be closer to the end. So this point here is 7.5 hours after Ryan left. So based off of this, you can see that Brian travels an extra 7.5 hours before his uncle begins to travel. And his uncle and him both traveled this portion here. And the only information we know about this portion Is that his uncle traveled 75 km At 50 km/h. So because we're given this sort of time in a distance Equation, we can calculate how much time it took him to travel those km. So it took him to if he drove a total of km and he was going 50 kilometers per hour. Notice how I want the hour to be the unit that I have left. And if I do it this way, I'm going to be left with kilometers squared over our. So I need to flip the numerator and denominator here, 50 km/h is the same as one hour per 50 km. And now you can see that when I do this multiplication, I have the correct units because the kilometers cancel out. So this leaves me with hours, 25 divided by 50 hours or half an hour is how long it took his uncle to get to the ports. So now we can fill in this timeline. Here and say that this is actually 0.5 hours. And now we can calculate the total time that Ryan traveled Because he traveled the 7.5 hours before His uncle started moving, plus the 0.5 hours that it took his uncle to get to the Pork. So that means that Ryan traveled for eight hours. And now to calculate the speed, we need to divide the distance by the time. So when we do that were given the distance, that's one of the first Numbers were given its 360 km divided by the total time which we calculated to be eight hours. And when you do 360 km divided by eight hours, we get 45 kilometers per hour. So if I write that Without the fraction, I can say 45 km/h. So that is the speed of the boat that Brian was traveling on to visit his uncle. And if we look at the answer choices, you can see answer choice C is also 45 km/h. So hopefully this video helped and see you next time.

Solve each problem. Speed of a PlaneMary Lynn left by plane to visit her mother in Louisiana, 420 km away. Fifteen minutes later, her mother left to meet her at the airport. She drove the 20 km to the airport at 40 km per hr, arriving just as the plane taxied in. What was the speed of the plane?

Key Concepts

Distance, Speed, and Time Relationship

Relative Motion

Unit Conversion

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