The spring shown in the figure is compressed 43 cm and used to launch a 100 kg p

Question

The spring shown in the figure is compressed 43 cm and used to launch a 100 kg physics student. The track is frictionless until it starts up the incline. The student's coefficient of kinetic friction on the 30 degree incline is 0.11. (Figure 1) What is the student's speed just after losing contact with the spring? Express your answer to two significant figures and include the appropriate units. How far up the incline does the student go? Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

(A) Applying energy conservation,

KEi + spring PEi = KEf+ spring PEf

0 + (80,000)(0.43^2)/2 = 100 v^2 /2 + 0

v = 12.2 m/s

(B) Applying work-energy theorem,

Work done by gravity + work done by friction = change in KE

{ on incline, N = 100 g cos30

f = uk N = 0.11 x 100 g cos30 =93.4 N}

(100 x 9.8 x 10) + (100 x 9.8 x - L sin30) + (- 93.4 L) = 0 - (100 x 12.2^2 / 2)

9800 - 490L - 93.4L = 7396

L = 4.12 m ......Ans

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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