Solving for Distance, Velocity and Acceleration

[jenny121]

Homework Statement

The distance moved by a mass is related to the time by x=3e^(0.4t) m. Find the following value after 5 sec

Relevant Equations

x=3e^(0.4t)

Distance:
substitute t=5 into x=3e^(0.4t)
22.17m

Velocity:
v=dx/dt
=1.2e^0.4t____(1)
Sub t=5 back into (1)
v= 8.867m/s

Acceleration:
a=dV/dt
=0.48e^0.4t____(2)
sub t=5 back into (2)
a= 3.547 m2/s

I am not sure if i am doing this right on dx/dt and dv/dt

 

[PeroK]

Your calculus looks fine. You might question the dimensional aspects of these equations, which the problem setter has chosen to ignore.

 

[haruspex]

Your calculus looks fine. You might question the dimensional aspects of these equations, which the problem setter has chosen to ignore.

It can be fixed by giving the time constant a unit:
$x=(3m)e^{(0.4s^{-1})t}$.
Those units then flow through to the answer.

 

[jenny121]

I see, thanks. after putting the unit it makes more sense now