In a laboratory experiment on friction, a 137N block resting on a rough horizont

Question

In a laboratory experiment on friction, a 137N block resting on a rough horizontal table is pulled by a horizontal wire. The pull gradually increases until the block begins to

move and continues to increase thereafter. the figure (Figure 1) shows a graph of the friction force on this block as a function of the pull.

Part A

Identify the regions of the graph where static and kinetic friction occur.

.

the friction is kinetic for P=0 to P=75.0 N, static for P>75.0 N.

or

the friction is static for P=0 to P=75.0 N, kinetic for P>75.0 N.

Part B

Find the coefficients of static and kinetic friction between the block and the table.

%u03BCs, %u03BCk =

Part C

Why does the graph slant upward in the first part but then level out?

Essay answers are limited to about 500 words (3800 characters maximum, including spaces).

Part D

What would the graph look like if a 137N brick were placed on the box, and what would be the coefficients of friction be in that case?

Essay answers are limited to about 500 words (3800 characters maximum, including spaces).

Explanation / Answer

F = uk N   :    75 = (137)g %u03BCk

uk = 75/137*9.8   =    0.05586

F = u N    :    50   = us (mg)

%u03BCs   =   0.0374

,kinetic friction is less than static friction , therefore there is a slant upto 75 N , when the block is at rest static friction is acting on it , as sonnas it starts moving , kinetic friction starts acting on it !!!!

It would remain the same as it does not depend on the mass of block put on surface , it depends on the nature of surface in contact !!!

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