# Worksheet: Free-Body Diagrams

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:

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

Q2:

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 ? Q3:

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

Q4:

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 Q5:

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

Q6:

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 Q7:

A free-body diagram representing the forces acting on an object is shown. What is the direction of the net force that acts on the object?

• AWest
• BEast
• CNorth
• DSouth

Which of the lines shown correctly represents the magnitude of the net force that acts on the object compared to the magnitude of the force that acts toward the west? • AII
• BIII
• CIV
• DI

Q8:

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

Q9:

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?

Q10:

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 Q11:

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 Q12:

Some forces act on a motorbike that moves toward the left, as shown in the diagram:

1. The drive force due to the motorbike’s wheels
2. Friction from the ground on the motorbike’s wheels that resist its forward motion
3. The weight of the motorbike
4. A vertical reaction force of the ground on each of the motorbike’s wheels Which of the following is a correct free-body diagram of the forces acting on the motorbike?

• A • B • C • D • E Q13:

Some forces act on a motorbike that moves toward the left, as shown in the diagram. These forces include the following:

1. The drive force due to the motorbike’s wheels
2. The friction of the ground on the bike’s wheels that resists its forward motion
3. The weight of the bike
4. The vertical reaction force of the ground on each of the bike’s wheels What is the net force toward the left that acts on the bike?

What is the magnitude of the vertical reaction force on either of the wheels of the bike?

Q14:

A man pushes a box in the direction of the arrow shown in the diagram and then removes his hand from the box. The box continues to move at a constant speed. Which of the following is a correct free body diagram showing the horizontal forces acting on the box after it has been released? • AIII
• BIV
• CII
• DI

Q15:

Some forces act on a motorbike. They include the following forces:

1. The horizontal reaction force from the ground on each of the bike’s wheels
2. The friction from the ground on the bike’s wheels that resists its forward motion
3. The weight of the bike
4. The vertical reaction force of the ground on each of the bike’s wheels

A free-body diagram of the forces acting on the bike is shown. The horizontal reaction force is shown by blue vectors, the vertical reaction force is shown by orange vectors, the friction force is shown by green vectors, and the weight is shown by a red vector. The bike moves toward the left. Which of the following is a correct diagram showing the forces acting on the bike?

• A • B • C • D • E 