crisss wrote:A drag racer, starting from rest, speeds up for 402 m with an acceleration of +17.0 m/s2. A parachute then opens, slowing the car down with an acceleration of -6.35 m/s2. How fast is the racer moving 2.95 102 m after the parachute opens?
Well this is a fairly easy question if you have studied SUVAT equations to any length. First off is to find the speed of the drag racer as the parachute opens, this can be done by using the equation V^2=U^2+2AS.
S = Displacement from original location
U = Starting velocity
V = Ending velocity
A = Acceleration
T = Time
Since we already know that the drag racer starts at rest we can simply put in the values which means that V is 116.91 M/S
From this we now have enough information to work out stage 2 of our calculation, if the parachute slows down the drag racer down by 6.35 M/S^2 then we should use the equation: DV=DTA (D stands for Delta which means the change in). Calculating this we get -18.7325 M/S
Taking this from our original value and we get that the speed of the drag racer 2.95 seconds after the parachute opens is 98.18 M/S after rounding.
OR If I misread your question and that 2.95 is not in seconds and is somehow irrelevant, then you can re-use the first equation with the distance from when the parachute was engaged and get an answer of 111.23 M/S.
