Answer:
18.25 units
Step-by-step explanation:
We are given that
The position of object A=
![A(t)=(3.00m/s)ti+(1.00m/s^2)t^2j](https://img.qammunity.org/2021/formulas/physics/college/tniyiiddyo8et4wiglca0bi4fd8q1i2jnt.png)
The position of object B=
![B(t)=(4.00m/s)ti+(-1.00m/s^2)t^2j](https://img.qammunity.org/2021/formulas/physics/college/wvqpkzvjm5mgvxqyvv2tos9swayo70lnbt.png)
We have to find the distance between object A and object at time t=3.00 s
Substitute t=3 s
![A(3)=9i+9j](https://img.qammunity.org/2021/formulas/physics/college/agfh1d0fs1x1l3cufv0j92ze9yqplmdu6b.png)
![B(3)=12i-9j](https://img.qammunity.org/2021/formulas/physics/college/17amxxpg87urjo2taezszrtlhsvibb0vvb.png)
The distance between A and B
![A(3)-B(3)=9i+9j-12i+9j=-3i+18j](https://img.qammunity.org/2021/formulas/physics/college/dmhwa6ofias2n37btgnr2g7ytf5pkus6qh.png)
The magnitude of distance between A and B
![\mid r\mid=√((-3)^2+(18)^2)=18.25 units](https://img.qammunity.org/2021/formulas/physics/college/ydxz96y54tx4r9serju2d37tcs2z4tl7i2.png)
Using the formula magnitude of position vector
r=xi+yj+zk
![\mid r\mid=√(x^2+y^2+z^2)](https://img.qammunity.org/2021/formulas/physics/college/jgq6r534mi83spcvnblfxe8gp8efwhgckm.png)