A race car is moving with a velocity of 144 kilometers/hour. The driver applies the brakes, and the car comes to a halt in 12.0
seconds. What is the acceleration of the car after 12.0 seconds?. a) -12.0 meters/second^2. b) -3.3 meters/second^2. c) 3.3 meters/second^2. d) 10.3 meters/second^2
To answer, first, convert the given velocity in km/h to m/s as shown below, (144 km / hr) x (1000 m / 1 km) x (1 hr / 3600 s) = 40 m/s The acceleration (a) is solved by through the equation, a = (Vf - Vi) / Δt where Vf and Vi are final and initial velocities, respectively and Δt is change in time. Substituting the known values, a = (0 - 40 m/s) / 12 s = -3.3 m/s² Thus, the answer to this item is letter B.
Velocity of the race car = 144 kilometers/hour It needs to be converted to meters per second because the answer is in meters per second. Then Velocity of the race car = <span>(144 km / hr) x (1000 m / 1 km) x (1 hr / 3600 s)</span> meters/second = 40 meters/second Initial velocity of the race car (V1) = 40 m/s Final velocity of the race car (V2) = 0 m/s Time taken by the car to come to a halt = 12 seconds Acceleration of the car = (V2 - V1)/time = (0 - 40)/12 = - 3.3 m/s^2 From the above deduction, we can conclude that the correct option among all the options that are given in the question is option "b".
