# Lesson Worksheet: Free-Body Diagrams Physics • 9th Grade

In this worksheet, we will practice analyzing free-body diagrams and use them to determine the net force and unknown forces acting on objects.

Q1:

In which of the following diagrams do the directions of all the vectors shown correctly represent the vectors in a free-body diagram of the forces acting on Earth due to the Sun’s gravity?

• A • B • C • D Q2:

The wheel of a car is rotating counterclockwise. The car is accelerating horizontally. The wheel makes contact with the road beneath it at a point that lies on the surface of the wheel, as shown in the diagram. Which of the following is a correct free-body diagram showing the forces acting on the point ?

• A • B • C • D Q3:

A box is pulled along a surface by an upward diagonal applied force of 55 N, as shown in the free-body diagram. The object does not move. Is the magnitude of the reaction force greater than, less than, or equal to 75 N?

• AMore than 75 N
• BLess than 75 N
• CEqual to 75 N

Is the magnitude of the friction force greater than, less than, or equal to 55 N?

• AMore than 55 N
• BLess than 55 N
• CEqual to 55 N

Q4:

A box is pulled along a surface by an applied force of 32 N, as shown in the diagram, which is not to scale. The net horizontal force on the box, acting to the right, is 24 N. What is the magnitude of the force ? Q5:

A free-body diagram representing the forces acting on an object is shown. Which of the following correctly shows the direction of the net force? • A • B • C • D • E Q6:

A free-body diagram representing the forces acting on an object is shown. What is the net vertical force acting on the object, taking the upward force as positive?

What is the net horizontal force acting on the object, taking the force toward the right as positive?

What is the magnitude of the net horizontal force acting on the object?

Q7:

A man pushes a box that is moving in the direction of the arrow shown in the diagram. Before the box touched the man’s hands, it was moving at a constant speed with no forces acting on it. Which of the following is a correct free-body diagram showing the horizontal forces acting on the box? • AIII
• BII
• CI

Q8:

A man pushes a box, as shown in the diagram. The box does not move. Which of the following is a correct free-body diagram showing the horizontal forces acting on the box? • AIII
• BI
• CIV
• DII

Q9:

A man pushes a box in the direction of the arrow shown in the diagram. Which of the following is a correct free-body diagram showing the horizontal forces acting on the box? • AIII
• BII
• CI
• DIV

Q10:

A stone is thrown horizontally toward the right from a boat and lands in the sea, where it sinks. Which of the following is a correct free-body diagram for the forces that act on the stone a very short time after it passes below the surface of the water?

• A • B • C • D • E 