Question

18:-A 25.0-kg block is released from rest at point A in the following Fig IHe ValXII frictionless except for the portion between points B and C, which has a length of 6.00 m. The block travels down the track, hits a spring of force constant 2250 N/m, and compresses the spring 0.300 m fro its equilibrium position before coming to rest momentarily. Determine the coef ficient of kinetic friction between the block and the rough surface between points B and C. (Height-3m). (A)0.43 (B)0. 16(C)0.33 (D)0.39 (E)0.41 A particle of mass m - 10.00 kg is released from point A and slides on the frictionless track shown in Fig.2 Q19:-Deier mine the particle's speed at pointB (A) 5.8ms-1 (B) 6.2ms1 (C) 5.6ms1 (D)6.00ms1 (E)6.4ms-1 020: the net wor k done by the gravitational force in moving the particle from A to B. (A)90) (B)1.62 (C)144) (D)126 (E)180) 6.00 m 5,00 m ll . II . TL'y 2.00 Fig.L Prob (18) Fig. 2 Prob (19.20

Answer 1

Using Energy conservation

final energy - initial energy = energy lost due to friction force

Initial energy = gravitational energy at the height of 3 m

Ei = m*g*h

final energy = Spring energy after spring spring compresses 0.300 m

Ef = (1/2)k*x^2

Energy lost due to friction = Ff*d

Ff = friction force = -uk*N = -uk*m*g

d = distance between B and C = 6 m

So,

Ef - Ei = Ff*d

(1/2)*k*x^2 - m*g*h = -uk*m*g*d

uk = (m*g*h - 0.5*k*x^2)/(m*g*d)

Using given values:

uk = (25*9.81*3 - 0.5*2250*0.300^2)/(25*9.81*6)

uk = coefficient of kinetic friction = 0.43

Correct option is A.

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