8. The coordinates of an object moving in R3 at time t are x = t, y = t2, z = (2/3)t3. What is the distance traveled by the object between t = 0 and t = 3 ?

 

A. 21

B. 27

C. 57

D. 75

E. 3(46)1/2

 

Solution: The answer is A

 

The distance traveled by the object between t = 0 and t = 3 is given by the length of the arc created by the object in R3 from t = 0 to t = 3.

The length, L, of an arc in R3 from t = a to t = b is given by,

Since

the distance traveled by the object is,