# Velocity from displacement

• Mar 14th 2010, 10:05 AM
yanmingfu
Velocity from displacement
Hi the question is as following,
The displacement of a body after time t is given as s = tsint + cost. Calculate its velocity and acceleration values at t = 3
(an: -2.970; -1.413)

I used equation ds/dt = v to find the derivative which is
v = tcost + sint -sint
but when i put t = 3 to the equation can't get the right answer, I thought it would be the problem of the derivation but I can't find which goes wrong.
(Crying)
• Mar 14th 2010, 05:59 PM
mr fantastic
Quote:

Originally Posted by yanmingfu
Hi the question is as following,
The displacement of a body after time t is given as s = tsint + cost. Calculate its velocity and acceleration values at t = 3
(an: -2.970; -1.413)

I used equation ds/dt = v to find the derivative which is
v = tcost + sint -sint
but when i put t = 3 to the equation can't get the right answer, I thought it would be the problem of the derivation but I can't find which goes wrong.
(Crying)