Question

A window scrubber is used to brush up a vertical window as shown in Fig. The brush weigh 12 N and coefficient of kinetic friction of 0.15. Calculate F

• A. 15 N
• B. 10.2 N
• C. 16.9 N
• D. 18.1 N

Answer 1

Answer: (C)

16.9 N

Answer 2

μN = mg + F sin 53; N = F cos 53

F =

= $\frac { 12 } { 0.8 - 0.15 \times ( 0.6 ) } = 16.9 \mathrm {~N}$.