A man tries to remain in steady state by pushing his feet...

Name: Problem 19, Chapter 5: Guide to Physics IIT JEE
Uploaded: 2021-07-01T02:32:19-08:00
Duration: 7 min 27 s
Channel: Cyra Jelle Calleja
Description: A man tries to remain in steady state by pushing his feet and hands against two parallel walls. Then for equilibrium (Figure can't copy) (a) force of friction should be equal on the two walls. (b) force exerted by him on both walls should be equal and the walls should not be frictionless. (c) he should press his feet with greater force. (d) coefficient of friction should be equal for both walls.

A man tries to remain in steady state by pushing his feet and hands against two parallel walls. Then for equilibrium (Figure can't copy) (a) force of friction should be equal on the two walls. (b) force exerted by him on both walls should be equal and the walls should not be frictionless. (c) he should press his feet with greater force. (d) coefficient of friction should be equal for both walls.

A man tries to remain in steady state by pushing his feet and hands against two parallel walls. Then for equilibrium
(Figure can't copy)
(a) force of friction should be equal on the two walls.
(b) force exerted by him on both walls should be equal and the walls should not be frictionless.
(c) he should press his feet with greater force.
(d) coefficient of friction should be equal for both walls.

Key Concepts

Coefficient of Friction

The coefficient of friction is a dimensionless constant that quantifies the ratio between the maximum frictional force and the normal force. It is fundamental in evaluating the effectiveness of friction in preventing motion and is a key parameter in problems involving contact forces.

Normal Force

The normal force is the perpendicular force exerted by a surface to support the weight of an object acting on it. In friction problems, this force is essential because it directly influences the magnitude of the static friction available for maintaining equilibrium.

Static Equilibrium

Static equilibrium refers to the state where an object remains at rest because the net force and net torque acting on it are zero. This concept is crucial in problems where multiple forces act on an object and must balance out to prevent motion.

Static Friction

Static friction is the force that resists the initiation of sliding motion between two surfaces in contact. It is directly proportional to the normal force and depends on the coefficient of friction, determining how much force is needed to prevent slipping.

Transcript

00:02 In this problem, we have a person that is resting between two walls by pushing his hands and feet on wall a and pushing his back on wall b.

00:17 The problem asks us for two things.

00:20 First, to show that the force exerted by the person in each wall is equal in magnitude and what is the normal force exerted by each wall on the person.

00:35 So to solve this problem, we have to apply newton's law of motion.

00:42 First, we will though the diagram of the forces acting on the person's body.

00:57 Shuming, this is the person and this is the wall.

01:05 The forces acting on the person are the normal force exerted by wall b, the normal force exerted by wall a, the weight of the force exerted by wall b, the normal force exerted by wall a, the weight of the the person and the friction force that is opposite the downward pull of the weight, which is both for each wall.

01:54 Now, to prove that the force exerted by person each wall are equal in magnitude, we have to write down the forces acting on the man or the person in the horizontal plane.

02:14 Applying first law of motion, since this person is at rest, then the net force on the horizontal plane acting on its body is equal to zero.

02:30 The forces on this plane are the normal force exerted by wall b, the normal force exerted by wall a.

02:50 This is negative since it's opposite, the normal force exerted by wall b.

02:56 Then equation becomes normal force exerted by wall b is equals to normal force exerted by wall a.

03:07 Thus, this means that normal force exerted by each wall is equal in magnitude.

03:32 But what the problem is asking is the force exerted by the person.

03:38 Now, we will apply third law of motion that states that in every action, there is an equal.

03:44 Wall in opposite reaction...

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