You have been called to testify as an expert witness in a trial involving a head

Question

You have been called to testify as an expert witness in a trial involving a head-on collision. Car A has a mass of 690.0 kg and was traveling eastward. Car B has a mass of 520.0 kg and was traveling westward at 72.0 km/h. The cars locked bumpers and slid eastward with their wheels locked for 6.00 m before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750. How fast (in kilometer per hour) was car A traveling just before the collision? (Express your answer to three significant figures.) km/h

Explanation / Answer

given

Ma = 690 kg

Mb = 520 kg

velocity = 72 km/h

distance = 6 m

using law of conservation of momentum

690 V1 - 520 V2 = 1210 V

690 V1 - 520 X 72 = 1210 V ------------     1

buit usig kinetic energy

KE = 0.5 m V2

KE = 0.5 X (1210 ) V2

PE = m g h

PE = 1210 X 9.8 X 0.75 X 6

PE = KE

0.5 X 1210 X V2 = 1210 X 0.75 X 9.8 X 6

V2 = 2 X 0.75 X 9.8 X 6

V2 = 88.2

V = 9.93 m/s = 35.74 km/hr

V value is substituting in the equation 1

690 V1 - 520 X 72 = 1210 X 35.74

690V1 = 43245.4 - 37440

V1 = 8.41 km / hr

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

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