Question

Determine the minimum force P to prevent the 25-kg rod AB from sliding. The contact surface at B is smooth, whereas the coefficient of static friction between the rod and the wall at A is μs = 0.17.

Answer 1

108.65 N

Step-by-step explanation:

given,

mass of road = 25 Kg

static friction at A = 0.17

contact force at B

there will a normal force acting at point A i.e Na and a friction force in the vertical direction at Point A i.e. μNa

A horizontal force is acting along point B i.e N_b.

At the middle weight of of the rod will be acting i.e mg at 2 m

diagram attached below shows the forces,

now, taking moment about point B

computing horizontal forces

`N_a * 4 + \mu N_a * 3 = m g * 2`

`N_a * 4 + 0.17 N_a * 3 = 25* 9.8 * 2`

`4.51N_a= 490`

Na= 108.65 N

now,

computing horizontal forces

P = N_a

P = 108.65 N

hence, P is the contact force at point B