Question

Problems 42 through 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram.

You are a rock climber going upward at a steady pace on a

vertical wall.

Short answer

A free-body diagram, motion diagram and force-identification diagram of a rock-climber moving with a constant pace is shown here. For this the person is considered as a particle model and represented by a dot.

Step-by-step solution

Motion diagram

* Consider the particle model for the diagram of the motion.

* Model the rock climber as a dot and assume the mass of the person is concentrated into a single point.

* The person is climbing a vertical wall with steady pace. So, the frame between two dots should be as the speed of the person is the same at each point of the wall.

* The velocity vector must be directed upwards.

* Thus, the motion diagram of the rock climber is shown below:

Force-identification diagram

To identify the force acted on the rock climber, we have to follow the given steps:

1. We have to consider the object in which the force is acting upon. Here, the object is the rock climber.
2. We can draw the image of the person and encircle it.
3. The following forces are acting on the person:

• A force of friction${\overrightarrow{f}}_s$is acted upon the person by the wall through which the person is climbing up. The frictional force is acting upward and dragging the person downward.
• The long range gravitational force${\overrightarrow{F}}_G$is acted downwards.

The force-identification diagram is shown below:

Free-body diagram

In free body diagram, a pictorial representation of an object is drawn which is under the influence of some forces. Here the objects act as the particle and the forces acting on the object.

To draw a free-body diagram, we have to follow some steps as given below:

• Draw a coordinate system.
• Identify all the forces acting on the rock climber and draw the vector of the forces.
• Affix the person representing him as a dot at the origin of the coordinate axes using the particle model.
• Here, a static frictional force is acted on the person along y-axis and as he is climbing along a vertical wall, there is no component of normal force acting vertically.
• A long range gravitational force is acted downwards along negative y-axis.

The net force acted on the person is zero. So, the rock climber is climbing upwards the vertical wall with constant pace as shown below: