Friday 1 May 2015

Speed Concepts (Divergence)

Given: Diverging Distance, Diverging Time, One Speed
Answer: Other Speed

First
Mr Lee and Mr Tan started driving from Point A in opposite directions. After driving for 4 hours, they were 660 km apart. If Mr Lee's driving speed was 100 km/h, find Mr Tan's average driving speed.


Given: Diverging Time, 2 Speeds
Answer: Diverging Distance


First
Timothy and Jane started jogging from the same place at the same time but in opposite directions along a straight road. Timothy's speed was 10km/h while Jane's speed was 8km/h. After jogging for 3 hours, how far apart were they?

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Total Speed = 10km/h + 8km/h
= 18km/h


Total Distance = 18km/h × 3h = 54km

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Given: Difference in Speed, Diverging Distance, Common Time
Answer: Fast or Slow Speed


First
Kerrine and Thompson started walking from the same starting point, but in opposite directions along a straight path.
Kerrine's average speed was 4 km/h more than Thomson's.
After walking for 3 hours, they were 40 km apart.
What was Kerrine's average walking speed.


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Difference in Distance = 4 km/h x 3 h = 12 km


Kerrine's Distance  = (40km + 12km) / 2 = 26 km


Kerrine's Speed = 26 km / 3 h = 8 2/3 km/h

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Second
Andy and Candy left their house at the same time and travelled in opposite directions.
Candy drove at a speed of 16km/h slower than Andy.
30 minutes later, Andy arrived at his destination, while Candy stopped for a rest.
They were 100km apart then.
Find Andy's speed.

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Difference in Distance = 16 km/h x 1/2 h = 8 km


Andy's Distance = (100 km + 8 km) / 2 = 54 km


Andy's Speed = 54 km / 1/2 h = 108 km/h

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