The aircraft A with radar detection equipment is flying horizontally at an altitude of 12 km and is increasing its speed at the rate of 1.2 m/s each second. Its radar locks onto an aircraft B flying in the same direction and in the same vertical plane at an altitude of 18 km. If A has a speed of 1000 km/h at the instant when θ = 30°, determine the values of ¨ r r¨ and ¨ θ θ¨ at this same instant if B has a constant speed of 1500 km/h.

An artesian well is simply a well that doesn't require a pump to bring water to the surface; this occurs when there is enough pressure in the aquifer. The pressure forces the water to the surface without any sort of assistance.

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key points:

• The Dubai Mall is the largest mall in the world.

• Area : the same as 50 football pitches and more than 1200 shops.

• ground floor have an aquarium, named Dubai Aquarium, the world's largest indoor aquarium.

• aquarium with 33 000 aquatic animals including sharks.

• outside the Mall, have fountains, named Dubai Fountains with water jets of approximately 200 metres long.

• can visit Olympic sized ice-skating rink.