Two cars 150 km apart drive toward each other at 60 km/h and 40 km/h. In how many hours will they intersect?
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Answer: D. 1.5
Explanation
Two cars moving toward each other have a relative speed equal to the sum of their individual speeds. Adding sixty kilometers per hour and forty kilometers per hour gives a combined speed of one hundred. Dividing the distance of one hundred fifty kilometers by one hundred gives an intersection time of one point five hours. Relative speed in opposite direction travel is the sum of the individual speeds of the moving bodies. Time equals the total distance between objects divided by their combined relative speed. Linear motion problems assume constant velocities throughout the entire duration of travel.
Air traffic controllers calculate closure rates and intersection times for aircraft flying on converging paths. Rail transport schedulers manage train crossings on single tracks using relative speed calculations. Automotive safety engineers analyze collision warning systems based on relative vehicle closure speeds. Option a overestimates the travel time by using a smaller relative speed calculation. Option b assumes a combined speed that is too low for the two vehicles combined. Option c results from an incorrect division of distance by relative velocity values.
- Subject
- Mathematics
- Category
- Mathematics
- Topic
- —
- Difficulty
- medium
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