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The speed of a is 6 m / s, and that of B is 4 m / s. After a few laps, can a surpass B by one lap?
400 × 2 ÷ (6-4) × 4 ／ 400 = 800 ／ 2 × 4 ／ 400, = 4 (LAPS). A: after 4 laps of B, a can surpass B by one lap
A and B practice the 100 meter race. They start from the starting point at the same time. A's speed is 7 m / s, and B's speed is 6.5 m / s. After 10 seconds, a's speed is reduced to 6 m / s because of twisting his foot. Can b catch up with a before reaching the 100 meter finish?
List the equations,
No. the time needed for a to reach the end: 100-7 * 10 = 30 / 6 = 5 seconds
B: 100-6.5 * 10 = 35 / 6 > 5
A and B go along the east-west highway at an average speed from west to East. A walks 3 kilometers per hour, B walks 2 kilometers more than a, and a passes by at 10 a.m·
A, B passed by a at 12:00 noon on the same day and asked B when to catch up with a in the afternoon and how far away from a?
Please write down your analysis ideas.
The speed of a is 3 km / h, and that of B is 3 + 2 = 5 km / h
Let the time of pursuit be x hours,
(5-3)X=2×3
2x=6
X = 3 (hours)
12 + 3 = 15
3 × 5 = 15 km
B can catch up with a at 15:00 p.m., 15 kilometers from a
A. The highway between city B is 522 kilometers long. Car a starts from city a and travels 75 kilometers per hour. Two hours later, car B starts from city B
Travel 80 kilometers per hour. How many hours after B starts to meet a car?
（522-75×2）÷（75+80）
=372÷155
=2.4 (hours)
A: car B meets car a 2.4 hours after departure
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