Highways in other counties have speed limit 100km/h. How does this compare with

Question

Highways in other counties have speed limit 100km/h. How does this compare with 7Omi/h speed limit in United States? In 2008 Beijing Olympic Usain Bolt of Jamaica set a world record in the 100-m dash with a time of 9.68 s. What was his average speed? If his acceleration is a constant and the initial speed is zero, what is his acceleration? You were driving at 60km/h when you applied constant acceleration to pass another car.6 seconds later, you were driving 80km/h. How far did you go in this time You walk north 200m, then east 100m. What are magnitude and direction of you displacement? The position of an object as a function of time is r = (3.2t + 1 .St^2)i + (1 7t - 2.4t^2)j m, with time t in second Find the object velocity and acceleration vectors.

Explanation / Answer

5) Resultant Displacement = sqrt[200^2 + 100^2] = 223.6 m

Direction = arctan(200/100) = 63.4 degree towards North from East.

6) r = (3.2t + 1.8t2) i + (1.7t - 2.4t2) j

velocity = v =dr/dt = (3.2 + 3.6t) i + (1.7 - 4.8t) j

Acc. = a = dv/dt = 3.6 i - 4.8 j

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