Asports car accelerates in third gear from 48.5 km/h to 80.2 km/h in 3.6 s. (a) what is the average acceleration of the car? (in m/s^2)
(b) if the car maintained this acceleration after reaching 80.2 km/h, how fast would it be moving 4.0 seconds later? (in km/h)

Explanation:

It is given that,

Initial velocity of the car, u = 48.5 km/h = 13.47 m/s

Final velocity of the car, v = 80.2 km/h = 22.27 m/s

Time, t = 3.6 s

(a) Average acceleration is given by :

(b) We need to find the final velocity after 4 seconds. From first equation of motion as :

v = u + a t

v = 32.07 m/s

or

v = 115.45 km/h

Hence, this is the required solution.

carla slowed down in the beginning of her trip, stopped, and then sped up

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.