A 1 kg block slides down a flat ramp, which has µk = 0.2. The length of the ramp

Question

A 1 kg block slides down a flat ramp, which has µk = 0.2. The length of the ramp is 2 meters. The ramp is at an angle of 30 to the horizontal.

a) If the block is released from rest at the top of the ramp, what is the speed of the block as it leaves the ramp? Use Newton’s Laws and kinematic methods to solve.

b) What is the work done by friction on the block?

c) What is the kinetic energy of the block as it leaves the ramp?

d) From part c), what is the speed of the block as it leaves the ramp. Does it agree with your answer in part a)?

e) What is the average power dissipated by friction while the block is sliding?

Explanation / Answer

acceleration   

mg sin 30 - Uk mg co 30 = m a

a = g sin 30 - Uk g cos 30 = 3.2 m/s^2

(a) u =0, v =??

V^2 - U^2 = 2 * a * S

V^2 - 0 = 2 * 3.2 * 2

V = 3.57 m/s

(b) work done, W = fk S = uk N * S = 0.2 * mg cos 30 * 2 = 0.2 * 1 * 9.8 * cos 30 * 2 = 3.39 J

(c) K. E = 1/2 m V^2 = 1/2 * 1 * 3.57^2 = 6.37 J

(d) yes

(e) V = u + a * t

3.57 = 0 + 3.2 * t

   t = 1.11 s

   power = 6.37 /1.11 = 5.738 W

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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