You push downward on a trunk at an angle 25° below the horizontal with a force of $750 \mathrm {~N}$ If the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61,what is the most massive trunk you will be able to move?
A)81 kg
B)93 kg
C)73 kg
D)112 kg

Question

Quizplus · Accepted Answer

The maximum force of static friction is:$$f_s=\mu_sn$$$$f_s=0.61n$$The normal force is:$$n=mg\cos25^\circ$$The force applied is:$$F=750	ext{ N}$$The angle between the force and the normal force is:$$	heta=90^\circ-25^\circ=65^\circ$$The maximum force of static friction is:$$f_s=\mu_sn=0.61mg\cos25^\circ$$The maximum force that can be applied without moving the trunk is:$$F=f_s=0.61mg\cos25^\circ$$The mass of the trunk is:$$m=\frac{F}{0.61g\cos25^\circ}=\frac{750	ext{ N}}{0.61(9.81	ext{ m/s}^2)\cos25^\circ}=93	ext{ kg}$$

You Push Downward on a Trunk at an Angle 25° 750 N750 \mathrm {~N}750 N

You Push Downward on a Trunk at an Angle 25° $750 \mathrm {~N}$