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Q. 55

Expert-verified
Found in: Page 130

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# A heavy box is in the back of a truck. The truck is accelerating to the right. Draw a motion diagram, a force-identification diagram, and a free-body diagram for the box .

A motion diagram, force-identification diagram, and free body diagram of a heavy box on the truck represent the direction of speed, its acceleration, and all the forces acting on the heavy box on the back of the truck.

See the step by step solution

## Given information

A heavy box is kept in the back of the truck that is accelerating towards the right.

## Motion diagram

• Consider the particle model for the diagram of the motion.
• Represent the truck as a dot and assume the mass of the heavy box in the back of a truck is concentrated into a single point considering the particle model.
• The acceleration vector is directed along in the direction of the motion of the truck.
• The motion diagram of the heavy box is in the back of a truck is shown below

## Force-identification diagram

To draw a force identification diagram, follow the step below.

• Identify the object of interest. Here, the object of interest is a heavy box on the back of the truck.
• Draw the object of interest and all other objects. Draw the heavy box on the back of the truck.
• Encircle the object of interest, that is, the heavy box on the back of the truck.
• Name and label the contact forces. The box is not sliding against the truck hence it is static friction. Static friction acts in the direction needed to prevent slipping. In this case, friction must act in the forward (toward the right) direction.
• Name and label the long-range force acting on the object. Here, the long-range force acting on the object is a gravitational force that is acting in a downward direction.
• The force identification diagram is shown below

## Free-body diagram

The free-body diagram is a pictorial representation of an object under some forces where the objects act as the particle and the forces acting on the object.

To draw a free-body diagram, follow the steps given below:

• Draw a coordinate system.
• Identify all the forces acting on the object and draw the vector of the forces.
• Represent the object (here, the heavy box) as a dot at the origin of the coordinate axes considering the particle model.
• A long-range gravitational force is acting on the heavy box.
• The free body diagram is shown below