Finding initial velocity and time Please

[Cyosis]

or with the formula u told me to use, would be:
t = (650 x 10^3) / 3157 = 206 secs

Remember x=v_x t. You entered the total speed, but instead you need to enter v_x=v cos(20). That's why you get a different answer.

 

[red_viper_88]

so which is the correct way to do it?
and what would u advise me to put as my final answer?

 

[Cyosis]

Picking either equations will do, however always pick the easiest to minimize the errors. Secondly for optimal accuracy don't calculate the cos/sin then round them and then use them in further calculation. Just keep them as cos/sin. Same for the other variables if you do that you get the following answers.

v=3149.61 m/s
t=219.619 s

You see that rounding constantly during the calculation introduces errors.

 

[red_viper_88]

thank you so much for all your time, help, and patience![/color]