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Rate-Time-Distance Problems. Algebra 1. Rate-Time-Distance Problems.
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Rate-Time-Distance Problems Algebra 1
Rate-Time-Distance Problems • An object is in uniform motion when it moves without changing its speed, or rate. These problems fall into 3 categories: Motion in opposite directions, Motion in the same direction, & Round Trip. Each is solved using a chart, a sketch, and the distance formula.
Motion in the Same Direction A helicopter leaves Central Airport and flies north at 180 mi/h. Twenty minutes later a plane leaves the airport and follows the helicopter at 330 mi/h. How long does it take the plane to overtake the helicopter. t + ⅓ 180 180(t + ⅓) 330 t 330t
180 t + ⅓ 180(t + ⅓) 330 t 330t When the plane overtakes the helicopter, the two distances are equal.
Officer Barbrady left his home at 2:15 PM and had driven 60 miles when he ran out of gas. He walked 2 miles to a gas station, where he arrived at 4:15 pm. If he drives 10 times as faster than he walks, how fast does he walk? 60 10r r 2
Set to Equal Office Barbrady walked at a rate of 4/mph
Rate Time Distance Sherry Bob Two cars leave the same town at the same time. One travels north at 60 mph and the other south at 45 mph. In how many hours will they be 420 miles apart? t Car #1 60 60t t 45t Car #2 45
Rate Time Distance Sherry Bob Car #1 60 t 60t 45 t 45t Car #2 In 4 hours the cars will be 420 miles apart.
Bicyclist Brent and Jane started at noon from 60 km apart and rode toward each other, meeting at 1:30 P.M. Brent’s speed was 4 km/h greater than Jane’s speed. Find their speeds. r + 4 1.5 1.5(r + 4) r 1.5 1.5r
r + 4 1.5(r + 4) 1.5 1.5 1.5r r
Round Trip A ski lift carried Maria up a slope at the rate of 6 km/h, and she skied back down parallel to the lift at 34 km/h. The round trip took 30 min. How far did she ski? 6 0.5 - t 6(0.5 – t) 34 t 34 t
Maria skied for 0.075h, or 4.5 min, for a distance of 2.55km. 6 0.5 - t 6(0.5 – t) 34 t 34 t In round trip problems, the two distances are equal.
Another fine lesson Given by the great teacher Mr. Stubbs THE END
Rate-Time-Distance Problems Review Additional Problems Part B
Rate Time Distance Sherry Bob Sherry and Bob like to jog in the park. Sherry can jog at 5 mph, while Bob can jog at 7 mph. If Sherry starts 30 minutes ahead of Bob, how long will it take Bob to catch up to Sherry? Let x = the time it takes Bob to catch Sherry x + 1/2 5(x + 1/2) 5 7 x 7x Sherry started 30 minutes or 1/2 hour before Bob, so her time must reflect that amount. Rate is in miles per hour, time must be in hours so our units match.
Rate Time Distance Sherry Bob x + 1/2 5(x + 1/2) 5 7 x 7x When Bob catches-up with Sherry their distances will be equal. So the Equation will be sherry’s distance equals Bob’s distance. It will take Bob 1.25 hrs to catch up with Sherry.
Bernadette drove 120 miles. The first part of the trip she averaged 60 mph, but on the second part of the trip she ran into some congestion and averaged 48 mph. If the total driving time was 2.2 hours, how much time did she spend at 60 mph? 60 60t t 48 2.2-t 48(2.2-t)
60 t 60t 2.2-t 48 48(2.2-t) The time traveled at 60 mph was 1.2 hours.
Rate Time Distance A passenger train’s speed is 60 mi/h, and a freight train’s speed is 40 mi/h. The passenger train travels the same distance in 1.5 h less time than the freight train. How long does each train take to make the trip. Freight train 4.5h. Passenger train 3h
Rate Time Distance Ali rode her bike to visit a friend. She traveled at 10 mi/h. While she was there, it began to rain. Her friend drove her home in a car traveling 25 mi/h. Ali took 1.5 hours longer to go to her friend’s than to return home. How many hours did it take Ali ti ride to her friend’s house? 2.5 h
Rate Time Distance Katie rides her bike the same distance as Jill walks. Katie rides her bike 10 km/h faster than Jill walks. If it takes Katie 1 h. and Jill 3 h to travel the same distance, how fast does each travel? Katie 15 km/ h Jill 5 km/h
Rate Time Distance At 10:00 A.M., a car leaves a house at a rate of 60 mi/h. At the same time, another car leaves the same house at a rate of 50 mi/h in the opposite direction. At what time will the car be 330 miles apart? 1:00 P.M.
Rate Time Distance Brittney begins walking ay 3 mi/h toward the library. Her friend meets her at the halfway point and drives her the rest of the way to the library. The distance to the library is 4 miles. How many hours did Marla walk? 2/3 h or 40 min.
Rate Time Distance Ryan begins walking towards John’s house at 3 mi/h. John leaves his house at the same time and walks towards Fred’s house on the same path at a rate of 2 mi/h. How long will it be before they meet if the distance between the houses is 4 miles? 4/5 h. or 48 min
Rate Time Distance A train leaves the station at 6:00 P.M. traveling west at 80 mi/h. On a parallel track, a second train leaves the station 3 hours later traveling west at 100 mi/h. At what time will the second train catch up with the first? 9:00 A.M.
Rate Time Distance It takes 1 hour longer to fly to St. Paul at 200 mi/h than it does to return at 250 mi/h. How far way is St. Paul. 1000 mi