1. The problem statement, all variables and given/known data A German U2 rocket from WW2 had a range of 300km, reaching a maximum height of 100km. Determine the rocket's maximum intial velocity. X component variables: di=0, df=300, a=0, time=9, vi=? Y component variables: a=-9.8, vf=0, vi=?, di=0, df=100, displacement=100, Note: For the y components, I counted the maxium height as the final position and the velocity at the max height as the final velocity. 2. Relevant equations The big 5 kinematics equations 3. The attempt at a solution I attempted to find the initial velocity for the x and y components and then use pythagorean theorem to solve for the magnitude of the max velocity as you would solve for the hypotenuse of a triangle and then I would use the cosine law to solve for the angle at which the rocket was launched. But, I got the incorrect magnitude after doing pythagorean theorem, so I stopped. Here's what I did: First, I calculated initial velocity for the y component, using the equation vf^2=vi^2+2a(displacement) --- I got vi=~44.3m/s. Then, I used another equation with the y component variables to solve for time because I needed another variable to use for the x component equations. For finding the time, I used displacement=1/2(vf+vi)(time). I got time=4.5s, but since the variables I used were variables only from the initial position to the max height, I think that using those variables only solved for the time up to the max height, so I multiplied by 2 to get the time for the whole motion--- 9 s. Then, I used the equation df=di+vi(time)+1/2a(t)^2. I got vi=33.3. Then, I used pythagorean theorem with the magnitudes of my x and y component velocities---- a^2=b^2-c^2 -- I plugged in the x and y component velocities for b and c and solved for a. I got a=55.4. This should've been equal to the magnitude of the max velocity, but the book says the answer is 1.75 x 10^3 m/s. Can someone tell me where I went wrong.