Two stationary cars are next to each other .At t=0s,car A begins accelerating (a

Question

Two stationary cars are next to each other .At t=0s,car A begins accelerating (a A =4m/s)but car B stalls.At t=5s ,car A stops accelerating and continus at a constant velocity,while Car B Finaly stars moving and accelerates at a rate of=5m/s aB=5 m/s2.                                  

a-) What is the speed of car A when car B starts moving?

b) how far ahead is Car A when Car B starts moving ?

c) At what time t does Car B catch up to Car A??

d)how far from the starting point does car B catch up to car A?

Explanation / Answer

(a)
vA = uA + aAt = 0 + 4*5 = 20 m/s

b)

sA = uA + (1/2)*aA*t2 = 0 + (1/2)*4*25 = 50m

c)

they both meet when sA = sB that is distances travelled by both are equal

so sA = 50 + 20*(t-5)

because 50 m is distance travelled during first 5s

sB = (1/2)*aB*(t-5)2

because car B started 5 sec later car A has started

so sB = (5/2)*(t-5)2

so sA = sB gives a quadratic for which solutions are

t = 15 and 3 but since t should be greater than 5

so answer is 15s

d) sB = (5/2)*(t-5)2 = 250m

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

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