Suppose the position of an object is given by a vector

AI Thread Summary
The position of an object is defined by the vector r = (3.0t²i - 6.0t³j) m. To find r at t = 2.5 s, substituting the value gives r = 3(2.5)²i - 6(2.5)³j, resulting in r = 18.75i - 73.002j. The answer was initially reported as 19i - 73j, but the user faced issues with the homework system marking it incorrect. After some confusion, the user received clarification and resolved the problem. Accurate calculations are crucial for correct submissions in physics assignments.
sunnyday
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Homework Statement


Suppose the position of an object is given by r⃗ = (3.0t2i^ - 6.0t3j^)m. Where t in seconds.

Determine r⃗ at time t = 2.5 s. Express your answer using two significant figures. Express your answer in terms of the unit vectors i^ and j^.

Homework Equations


plugging in 2.5 seconds to the r equation

The Attempt at a Solution


r = 3(2.5)^2i-6(2.5)^3j -> 18.75i-73.002j -> 19i-73j

When I put this answer in my homework, it says it's wrong. I even tried (19i-73j) and it says it's wrong.
 
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sunnyday said:
6(2.5)^3
Yes.
sunnyday said:
73.002
No.
 
  • Like
Likes sunnyday
haruspex said:
Yes.

No.
oh what. nvm. that was so weird. thank u so much!
 

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