Question

PHYSIC: 2 OBJECTS, 2 ACCELERATION.

Question 3 (2 objects 2 accelerations) Two cars are lined up for a drag race. On start, both cars accelerate with different constant acceleration. When car A reaches the finish line 200 meters away, car B is 80 meters ahead of car A traveling at 50 m/s. a. How much time did the race take? b. What was the acceleration of car B? c. What was the acceleration of car A? d. How fast was car A traveling at the finish line?

Answer 1

Let acceleration of car A be a and that of car B be b m/s^2 In the time car A reaches finish line that is covered 200 m, car B reaches (200 + 80) = 280 m with speed of 50 m/s. Both start from rest so initial velocity = 0 m/s So, By Newton's Law of motion \r\n For Car B. S = at + 1/2 bt^2 280 = 1/2 bt^2 (1) Also, v = u + bt 50 = bt Solving (1) and (2), we get t = 11.2 s b = 4.46 m/s^2 For Car B, same time will car A take to reach 200 m S = ut + 1/2 at^2 200 = 1/2 times at^2 [t = 11.2 s] a = 400/(11.2)^2 m/s^2 = 3.19 m/s^2 So, a) time = 11.2 s b) acc^n of car B = 4.46 m/s^2 c) acc^n of car A = 3.19 m/s^2. d) Speed of car