Understanding Vector Diagrams

Name:

Date:

📘 Part 1: Diagrams and Explanations

Diagram 1 — Single Net Force

A single large arrow pointing right represents one unbalanced force acting on an object. The net force is to the right, so the object will accelerate in that direction.

Diagram 2 — Equal and Opposite Forces (Balanced)

Two equal arrows, one left and one right, show forces of the same magnitude acting on an object. These balance, so the net force is zero and the object remains at constant velocity (including at rest).

Diagram 3 — Two Forces in Same Direction (Net Force)

Two arrows both pointing right but with different sizes add together. The net force is the vector sum (bigger arrow to the right). The object accelerates to the right with strength equal to the sum (in newtons).

Diagram 4 — Friction Opposing Motion

An applied force arrow to the right and a smaller friction arrow to the left show how friction reduces the net force. Friction always points opposite the motion (or attempted motion) along the contact surface.

Diagram 5 — Gravity and Normal Force (Flat Surface)

A downward arrow (gravity, mg) and an equal upward arrow (normal force) act on a stationary object on a flat surface. These two vertical forces are equal in magnitude (newtons) and opposite in direction when there is no vertical acceleration.

Diagram 6 — Inclined Plane: Components of Gravity

Gravity acts downward; on a slope it can be resolved into a component parallel to the plane (pulling down the slope) and a component perpendicular to the plane (balanced by the normal force). Friction acts opposite the parallel component when present.

Diagram 7 — Gravity and Air Resistance (Terminal Velocity)

A falling object may experience gravity downward and air resistance upward. If air resistance grows to equal gravity, the forces balance (net force zero) and the object reaches terminal velocity (constant speed).

📝 Part 2: Multiple Choice (Select the best answer)

1. In Diagram 1 (single arrow to the right), which is true?

The object has zero net force.

The object will accelerate to the right.

The object will accelerate to the left.

The object must be at rest and stay at rest.

2. In Diagram 2 (equal opposite arrows), what is the net force?

Equal to one of the forces.

Zero newtons.

Twice the larger force.

Depends on mass only.

3. In Diagram 3 (two arrows right of 3 N and 5 N), what is the net force?

2 N to the left

8 N to the right

5 N upward

15 N to the right

4. For Diagram 4 (applied force right 10 N, friction left 4 N), the acceleration direction is:

Left, because friction always wins.

Right, because net force is to the right.

Upward, because of normal force.

Zero, forces cancel exactly.

5. In Diagram 5 (gravity down 50 N, normal up 50 N), what is true?

The object is accelerating downward at 9.8 m/s².

The net vertical force is zero.

Normal force must be less than gravity.

Friction equals gravity.

6. On an incline (Diagram 6), the component of gravity that pulls the object down the slope is:

Equal to the normal force.

The component parallel to the plane.

Zero whenever there is friction.

Always upward along the slope.

7. In Diagram 7 (falling object), terminal velocity happens when:

Gravity is greater than air resistance.

Air resistance exceeds gravity.

Air resistance equals gravity (net force zero).

There is no gravity.

8. Two forces: 8 N left and 3 N right. Net force is:

11 N right

5 N left

5 N right

Zero newtons

9. According to Newton's third law, when a book pushes down on a table with 20 N, the table pushes up on the book with:

0 N (no reaction)

10 N

20 N upward

20 N downward

10. If an object on a flat surface has 30 N gravity and 25 N normal force upward, the object:

Accelerates upward

Accelerates downward

Has zero net force

Is in equilibrium horizontally

🔑 Answer Key (Instructor use)

1. The object will accelerate to the right. → B

2. Zero newtons. → B

3. 8 N to the right. → B

4. Right, because net force is to the right. → B

5. The net vertical force is zero. → B

6. The component parallel to the plane. → B

7. Air resistance equals gravity (net force zero). → C

8. 5 N left. → B

9. 20 N upward. → C

10. Accelerates downward (net 5 N down). → B

Note: Diagrams 1–7 are for student sketching and reinforcement of concepts: net forces, balanced vs. unbalanced, friction direction, gravity vs. normal, components on inclines, and terminal velocity.