Question

Physics Name (Print) 2.6 Solving One-Dimensional Motion Problems 21. Draw a pictorial representation of each situation describsed below. That is, () sketch the 1D inematks Actlwity 9Ww Section situation, showing appropriate points in the motion.(i) establish a coordinate system on your sketch, and (ii) define appropriate symbols for the known and unknown quantikies. Do not solve. See textbook Example 2.10 as an example. a. A car traveling at 30 m/s screeches to a halt, leaving 55-m-long skid marks. What was the car's acceleration while braking? Sketch with coordinate system: List of known kinematic variables (with sign) Unknown kinematic variable(s) that must be included in order to solve Which kinematic equation would you choose if you had to solve this? How do you know?

Answer 1

(A) Car travels at 30 m/s leaving 55 m long since area under velocity time graph is equal to displacement 1/2 times 30 times t = 55 t = 110/3 v^2 minus u^2 = 2 as v = 0, u = 30, s = 55 so (30)^2/2 times 55 = a = 8.18 m/s^2 Ans C u = 12 v = 0 a = 6 m/s^2 v^2 minus u^2 = 2 as (12)^2 = 2 times 6 times s s = 12 m total distance travelled = 12m times Reaction time velocity of car = 12m times 0.8 times 12 = 12 + 9.6 = 21.6 m Ans