*Chapter 2, Problem 34 In the figure here, a red car and a green car move toward

Question

*Chapter 2, Problem 34




In the figure here, a red car and a green car move toward each other in adjacent lanes and parallel to an x axis. At time t = 0, the red car is at xr = 0 and the green car is at xg = 216 m. If the red car has a constant velocity of 20.0 km/h, the cars pass each other at x = 43.6 m. On the other hand, if the red car has a constant velocity of 40.0 km/h, they pass each other at x = 76.6 m. What are (a) the initial velocity (in km/h) and (b) the (constant) acceleration (in m/s2) of the green car? Include the signs.



(a) Number *1 Unit km/h
(b) Number *2 Unit m/s^2

Answer *1: the tolerance is +/-3%
Answer *2: the tolerance is +/-3%

Explanation / Answer

Assuming initial velocity of green car = v & acceleration = a

In intial case

Vr = 20 km/h = 20*1000/3600 = 50/9 m/s

t = 43.6/(50/9) = 7.848 s

distance travelled by green car = 216-43.6 = 172.4 m

=> 172.4 = v*(7.848) + (1/2)*a*(7.848)2 ----------- eqn 1

In Second case

Vr = 40 km/h = 100/9 m/s

t = 76.6/(100/9) = 6.894 s

Distance travelled by green car = 216 - 76.6 = 139.4 m

=> 139.4 = v*(6.894) + (1/2)*a*(6.894)2 -------- eqn 2

Solving eqn 1 & 2

(a) v = 7.597 m/s = 27.35 km/h

(b) a = 3.66 m/s2

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.