Respuesta :
Answer:
(a) Magnitude of static friction force is 109 N
(b) Minimum possible value of static friction is 0.356
Solution:
As per the question;
Horizontal force exerted by the girl, F = 109 N
Mass of the crate, m = 31.2 kg
Now,
(a) To calculate the magnitude of static friction force:
Since, the crate is at rest, the forces on the crate are balanced and thus the horizontal force is equal to the frictional force, f:
F = f = 109 N
(b) The maximum possible force of friction between the floor and the crate is given by:
[tex]f_{m} = \mu_{s}N[/tex]
where
N = Normal reaction = mg
Thus
[tex]f_{m} = \mu_{s}mg[/tex]
For the crate to remain at rest, The force exerted on the crate must be less than or equal to the maximum force of friction.
[tex]f\leq f_{m}[/tex]
[tex]f \leq \mu_{s}mg[/tex]
[tex]109 \leq \mu_{s}\times 31.2\times 9.8[/tex]
[tex]\mu_{s}\geq 0.356[/tex]
