1. The problem statement, all variables and given/known data The position function of a projectile is given by r(t) = (5t + 6t2) m I + (30 - t3) m j. What is the displacement of the particle in magnitude angle form at the = 2.0 seconds. 2. Relevant equations √x2+y2 tan-1 = y/x Possibly: x = v0t + 1/2at2 3. The attempt at a solution I assumed you could calculate the position at t = 2.0 s by plugging into the position function and subtract the initial position. So the initial position would be 30 in the positive you direction (j) and 0 i. The position at t = 2.0 s would be 10 + 6 * 4 = 34 i and 30 - 8 = 22. So the displacement would then be 34 m in the positive x direction and 8 meters in the negative y directions The resultant magnitude would be √(34)2+(-8)2 = √1156 + 64 = √1220. The angle would be tan-1θ = y over x then Is this correct? I haven't encountered another problem finding displacement given position function. Or should I find initial velocity and acceleration and use x = v0t + 1/2at2.