# Position of an object in time and force (1 Viewer)

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#### preluderacer

1. The problem statement, all variables and given/known data

The position of an object as a function of time is given by = bt^3 ihat + ct jhat . If and , what is the force on a 2.0 kg object when t = 1.8 s?

3. The attempt at a solution

I tried multiplying it and got m ihat + m jhat. I don't even know where to begin.

#### rl.bhat

Homework Helper
If and , what is the force on a 2.0 kg object when t = 1.8 s?

This statement is not clear. Rewrite it.

#### preluderacer

The position of an object as a function of time is given by = bt^3 ihat + ct jhat . If b=2.1m/s^3 and c=1.7m/s, what is the force on a 2.0kg object when t=1.8s

#### rl.bhat

Homework Helper
Let x = bt^3 ihat + ct jhat
Find a = d^2(x)/dt^2 and substitute t = 1.8 s
Now find F.

#### preluderacer

so x=(bt^3ihat +ct)?

then u want me to find the derivative?

#### preluderacer

Ha, I went to get breakfast and kept thinking about it. It goes position, velocity, then acceleration. So I take the 2nd derivative with respect to time, then use f=ma. Thanks you!! =)

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