A car accelerates from rest at a rate of 2.5 m/s^2 as a traffic light turns gree

Question

A car accelerates from rest at a rate of 2.5 m/s^2 as a traffic light turns green. A pickup truck, timing the light perfectly in other lane passes the car just as the car begins to accelerate. The truck is traveling at a constant velocity of 10 m/s. If the car keeps the same acceleration and the truck keeps the same velocity,

A. How far from the stoplight will they be when the car catches up to the truck?

B. How much time has passed after the light turned green until the car catches the truck?

C. How fast is the car going when it passes the truck?

Explanation / Answer

let the distance covered by both of them when they meet = s and time after the green light when they meet, = t

so for car s= 0.5at2 or s= 0.5(2.5)t2 ......equation 1

and for truck, s=vt = 10t .......equation 2

dividing equation 1 by equation 2

we get:

t/8 = 1

or t= 8s

from equation 2 we get

s= 8 x 10 = 80m

A) 80 m

B) 8 seconds

now C part:

when they meet, velocity of car is given by

V = U + at

as U = 0 (as car was at rest initially)

V = at = 2.5 x 8 = 20m/s

so

C) 20m/s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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