Applied Mechanics Tutorials -2

Diploma in Civil Engineering

Applied Mechanics

Tutorials -2

A block of mass M = 10 kg is sitting on a surface inclined at angle θ = 45°. Given that the coefficient of static friction is μs = 0.5 between block and surface, what is the minimum force F necessary to prevent slipping? What is the maximum force F that can be exerted without causing the block to slip? 

ANS: Fmin = 34.65 N, Fmax = 103.94 N 


In the previous problem use θ = 15°. What is the maximum force pushing down the incline so that the block doesn't slip? What is the maximum force pushing up the incline so that the block doesn't slip? 
Answer: Fmax = 21.97 N (pushing down the incline), Fmax = 72.69 N (pushing up the incline) 


A block weighing 80 N rests on a plane inclined at 30 degrees to the horizontal. The coefficients of static and kinetic friction are 0.2 and 0.1 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?
Answer: F= 26N


A car (m=2000 kg) is parked on a road that rises 20 degrees above the horizontal. What are the magnitudes of (1) the normal force and (2) the static frictional force that the ground exerts on the tires?
 Answer :normal force:1.8x10^4N static friction force:6.7x10^3N

Important Topic

Friction and Laws of Static friction

Limiting Friction

Angle of Friction Coefficient of Friction