Forces and Motion Worksheet

Learning Objectives

By completing this worksheet, you will be able to:

• Define and identify forces in everyday situations
• Explain the concept of net force
• Distinguish between mass and weight
• Understand acceleration and how it differs from velocity
• Apply Newton's Second Law of Motion

Part 1: Forces in Everyday Life

1.1 What is a Force?

A force is a push or pull that can cause an object to change its motion. Forces are vector quantities, meaning they have both magnitude and direction.

Task 1: List five examples of forces you encounter in your daily life. For each example, identify whether the force is a push or a pull.

1. _____________________________
2. _____________________________
3. _____________________________
4. _____________________________
5. _____________________________

1.2 Types of Forces

Task 2: Match each force with its correct description:

Descriptions:

• The force that pulls objects toward the center of the Earth
• The force that opposes the motion of objects in contact
• The force exerted by a surface perpendicular to the object resting on it
• The force exerted when an object is pulled by a rope or string
• The force directly applied by a person or object to another object

Part 2: Net Force

2.1 Understanding Net Force

The net force is the vector sum of all forces acting on an object. It determines whether an object will accelerate and in what direction.

Task 3: Calculate the net force for the following scenarios:

a) A box is pushed to the right with a force of 15 N and to the left with a force of 10 N. Net force = _____________________________

b) A ball experiences a force of 5 N upward and 8 N downward. Net force = _____________________________

c) A car experiences a forward driving force of 2000 N and a backward drag force of 500 N. Net force = _____________________________

2.2 Free-body Diagrams

Task 4: Draw a free-body diagram for each of the following situations, showing all forces acting on the object:

a) A book resting on a table

b) A person standing in an elevator that is accelerating upward

c) A car moving at constant speed on a flat road

Part 3: Mass vs. Weight

3.1 Defining Mass and Weight

Mass is a measure of the amount of matter in an object. Weight is the force of gravity acting on an object.

Task 5: Complete the following statements:

a) Mass is measured in units of __________________.

b) Weight is measured in units of __________________.

c) The relationship between mass (m) and weight (W) on Earth is: $$ W = __________________ $$

d) An astronaut's mass on the Moon compared to Earth is __________________ (same/different), while their weight is __________________ (same/different).

3.2 Comparing Mass and Weight

Task 6: A person has a mass of 70 kg on Earth.

a) Calculate their weight in newtons on Earth (g = 9.8 m/s²): $$ W = __________________ $$

b) Calculate their weight on the Moon, where gravity is 1/6 of Earth's:

$$ W_{moon} = __________________ $$

c) What would be their mass on the Moon? Explain your answer.

Part 4: Acceleration and Velocity

4.1 Definitions

Velocity is the rate of change of position with respect to time, including direction. Acceleration is the rate of change of velocity with respect to time.

Task 7: Fill in the blanks:

a) Velocity is measured in units of __________________.

b) Acceleration is measured in units of __________________.

c) An object can have constant velocity but non-zero acceleration when __________________.

4.2 Distinguishing Velocity and Acceleration

Task 8: Identify whether each scenario describes velocity, acceleration, or both:

a) A car travels at 60 km/h east. __________________

b) A car speeds up from 0 to 60 km/h in 8 seconds. __________________

c) A ball is thrown straight up and momentarily stops at its highest point. __________________

d) A train rounds a curve at constant speed. __________________

e) A ball falls from a height, moving faster as it falls. __________________

Part 5: Newton's Second Law

5.1 Understanding F = ma

Newton's Second Law states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass.

Task 9: State Newton's Second Law in your own words:

5.2 Applying Newton's Second Law

Task 10: Solve the following problems:

a) A 2 kg object experiences a net force of 6 N. Calculate its acceleration.

$$a = \frac{F}{m} = \frac{____}{____} = ____ \text{ m/s}^2$$

b) A 1500 kg car accelerates at 2 m/s². Calculate the net force required.

$$F = m \times a = ____ \times ____ = ____ \text{ N}$$

c) A net force of 250 N produces an acceleration of 5 m/s² on an object. Calculate the object's mass.

$$m = \frac{F}{a} = \frac{____}{____} = ____ \text{ kg}$$

5.3 Critical Thinking

Task 11: A 50 kg box is resting on a horizontal surface. A person pushes horizontally with a force of 200 N. If the box doesn't move, explain what other force(s) must be acting and their values.

Part 6: Synthesis

Task 12: A rocket of mass 20,000 kg experiences a thrust force of 600,000 N upward and a gravitational force of 196,000 N downward.

a) Draw a free-body diagram showing all forces.




b) Calculate the net force on the rocket.

$$F_{net} = ____________________$$

c) Calculate the rocket's acceleration. $$ a = ____________________ $$

d) If the rocket's mass decreases as fuel is used, would its acceleration increase, decrease, or stay the same (assuming the thrust remains constant)? Explain your reasoning.