a bus travels 3 km in first 10 minutes,8km in next 10 minutes,10km in next 10 minutes and 14 km in next 10 minutes. what type of motion is exhibited by this train? Calculate its average speed in m/ s
Answers
Type 1. formula for Speed = Distance (in unit of length)/Time (in unit of time)
Illustration 1: A car travels a distance of 500 km in 10 hours. What is its speed in km/hr?
Sol: Speed = Distance/Time → 500/10 = 50 km/hr.
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Illustration 2: Aman can run a distance of 100 m in 20 seconds. Find the speed of Aman in m/s.
Sol: Speed = Distance/Time → 100/20 = 5 m/s.
Illustration 3: The distance between two stations is 540 km. A train takes 3 hours to cover this distance. Calculate the speed of the train in km/hr and m/s.
Sol: Speed = Distance/Time = 540/3x180 km/hr. To convert speed into m/s we need to multiply 180 by 5/18. So required speed = 180 × 5/18 = 50 m/s.
Type 2. Speed and distance formula: Average Speed = Total Distance Travelled/Total Time Taken
Illustration 4: Suraj drives first 120 km in 2 hrs and next 180 km in next 4 hrs. What is his average speed for the entire trip in km per hour?
Sol: Total Distance travelled = 120 + 180 = 300 km. Total Time taken = 2 + 4 = 6 hrs.
Average Speed =Total Distance Travelled/Total Time Taken = 300/6 = 50 km/hr.
Illustration 5: A train covered first 120 km at a speed of 20 km an hour and then covered the remaining 180 km at a speed of 45 km an hour. Find its average speed.
Sol: Total distance = 120 + 180 = 300 km. Time taken for the first 120 km = 120/20 → 6 hrs.
Time taken for the next 180 km = 180/45 → 4 hrs. Total time taken = 6 + 4 = 10 hrs.
Average Speed =Total Distance Travelled/Total Time Taken = 300/10 = 30 km/hr.
Illustration 6: A cyclist travels at 10 km/hr for 2 hours and then at 13 km/hr for 1 hour. Find his average speed.
Sol: Distance travelled in first 2 hours =10 × 2 = 20 km. Distance travelled in next 1 hour =13 × 1 = 13 km. Total Distance travelled = 20 + 13 = 33 km. Total time taken = 2 + 1 = 3 hrs.
Average Speed =Total Distance Travelled/Total Time Taken =33/3 = 11 km/hr.
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