(a) A block with a mass m is pulled along a horizontal surface for a distance x

Question

(a) A block with a mass m is pulled along a horizontal surface for a distance x by a constant force F at an angle ? with respect to the horizontal. The coefficient of kinetic friction between block and table is µk. Is the force exerted by friction equal to µkmg? If not, what is the force exerted by friction? (b) How much work is done by the friction force and by F ? (Don’t forget the signs.) (c) Identify all the forces that do no work on the block. (d) Let m = 2.00 kg, x = 4.00 m,  = 37.0°, F = 15.0 N, and µk = 0.400, and find the answers to parts (a) and (b).

Explanation / Answer

(A) The net force on the block

F = Fcos - f

F = mg cos - kmg

F = mg ( cos - k )

(B) The workdone by the friction force, W = f * x = kmg * x

(C) The vertical component of applied force does not acts on the block, and the normal

force does not work on the block.

(D) Answer to part A : F = 2*9.8 ( cos37 - 0.4 ) = 7.8 N

Answer to part B : W = 0.4 * 2 * 9.8 * 4 = 62.72 J

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

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