Velocity/displacement problem

  • #1

Homework Statement


For each function, find an expression for the velocity and the value of the displacement and velocity at t=5. Displacement is in metres and time is in seconds.

Homework Equations


A)[/B] s(t) = 3t + 7

B) s(t) = t3 - 2t2 + 4t - 1


The Attempt at a Solution



A) [/B]s(t) = 3t + 7
s(5) = 3(5) + 7
= 22 m/s

B) s(t) = t3 - 2t2 + 4t - 1
s(5) = 53 - 2(5) + 4(5) - 1
=94 m/s

 

Answers and Replies

  • #2
SteamKing
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Homework Statement


For each function, find an expression for the velocity and the value of the displacement and velocity at t=5. Displacement is in metres and time is in seconds.

Homework Equations


A)[/B] s(t) = 3t + 7

B) s(t) = t3 - 2t2 + 4t - 1


The Attempt at a Solution



A) [/B]s(t) = 3t + 7
s(5) = 3(5) + 7
= 22 m/s

B) s(t) = t3 - 2t2 + 4t - 1
s(5) = 53 - 2(5) + 4(5) - 1
=94 m/s
s usually denotes position or displacement, not velocity. How do you find velocity from displacement?

Remember, the problem is asking you to find both displacement and velocity at a given time, t.

Hint: You posted this problem in the Calculus HW forum, yet you used no calculus. Didn't you find that a little odd?
 

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