A) The driver of a truck slams on the brakes whenhe sees a tree blocking the roa

Question

A)The driver of a truck slams on the brakes whenhe sees a tree blocking the road. The truck slows down uniformlywith acceleration -5.3 m/s2 for4.20 s, making skid marks 59.7 m long thatend at the tree. With what speed does the truck then strike thetree?
1 m/s

B)A certain freely falling object requires 1.15 s to travel the last 22.0 m before it hits the ground. From what heightabove the ground did it fall?
1 m

C)The driver of a truck slams on the brakes whenhe sees a tree blocking the road. The truck slows down uniformlywith acceleration -5.3 m/s2 for4.20 s, making skid marks 59.7 m long thatend at the tree. With what speed does the truck then strike thetree?
1 m/s

D)A certain freely falling object requires1.15 s to travel the last 22.0 m before it hits the ground. From what heightabove the ground did it fall?
1 m

Explanation / Answer

Let u be the initial speed of the truck and v be the final velocityof the truck when it hits the truck. We know the formula v = u + at                                   v = u + (-5.3m/s2)(4.20s)                                      = u - 22.26m/s                               v - u = -22.26m/s .................. (1) And v2 - u2 = 2aS       (v + u)(v - u) =2(-5.3m/s2)(59.7m)         (v + u)(-22.26m/s) =-632.82m2/s2           v + u =28.43m/s ................ (2) Adding the eq (1) and (2) we get         2v = 28.43m/s -22.26m/s          v = 3.08m/s Therefore the speed of the truck when it hits the tree is3.08m/s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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