ou are to drive to an interview in another town, at a distance of 300 km on an expressway. The interview is at 11:15 a. m. You plan to drive at 100 km/h, so you leave at 8:00 a. m. to allow some extra time. You drive at that speed for the first 100 km, but then construction work forces you to slow to 40.0 km/h for 43.0 km. What would be the least speed (in km/h) needed for the rest of the trip to arrive in time for the interview?

Question

Physics

Ezequiel Powell

23 August, 13:59

ou are to drive to an interview in another town, at a distance of 300 km on an expressway. The interview is at 11:15 a. m. You plan to drive at 100 km/h, so you leave at 8:00 a. m. to allow some extra time. You drive at that speed for the first 100 km, but then construction work forces you to slow to 40.0 km/h for 43.0 km. What would be the least speed (in km/h) needed for the rest of the trip to arrive in time for the interview?

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Answers (1)

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Marques Duarte · Answer 1

133.62 kmh.

Explanation:

Time provided = 3.25 hours.

Distance to be covered 300 km

Times spent in first 100 km = 1 hour

Time spent in next 43 km

= 43 / 40 = 1.075 hours

Total time spent = 2.075 hours

Total distance covered = 143 km

Distance remaining = 300 - 143

=157 km.

Time remaining = 3.25 - 2.075

= 1.175

Speed required = Distance remaining / time remaining

= 157 / 1.175

= 133.62 kmh.