Newton’s Three Laws of Motion Handout

Introduction:

Sir Isaac Newton’s three laws of motion are fundamental principles in classical mechanics, which describe the relationship between an object and the forces acting upon it. They explain many of the events seen everyday, such as the motion of a car, the launch of a rocket, or a baseball flying through the air. The three laws are the forces that an object experiences are equal and opposite, an object remains in its state of rest or uniform motion in a straight line until it is acted upon by an external force, and for every action, there is an equal and opposite reaction.

Law 1: Every object continues in its state of rest or uniform motion in a straight line, unless it is compelled to change that state by forces impressed on it.

Formula: F = m*a

Worked Example: A car is traveling down a highway at a constant speed of 25 m/s. Calculate the force required to keep the car in motion. Answer: Since the car is moving at a constant speed, no force needs to be applied to keep it in motion. The only force needed to keep the car in motion is the force of friction, which is keeping the car from slowing down due to the force of gravity.

Questions: 1. What is the difference between acceleration and velocity? 2. What is the relationship between a force and acceleration? 3. How can a force alter the motion of an object? 4. What type of force is needed to keep an object in motion? 5. If two objects are moving in opposite directions, can they both be affected by the same force?

Numerical Questions: 1. An 8 kg sled is pulled across a level snow field at an acceleration of 2 m/s2. How much force is required? 2. A 2000 kg car is driving down a highway at a constant speed of 70 km/h. What is the force required to keep the car in motion? 3. A 10 N force is applied to a 3 kg block. What is the acceleration of the block? 4. A cyclist is riding a bike with a mass of 97 kg up a hill with a gradient of 6%. How much force is needed to keep the bike moving at a constant speed? 5. A 50 N force is applied to a 10 kg block. What is its acceleration? 6. A 10 N force is acting on a 1 kg object. What is its acceleration? 7. A 0.2 kg object is acted upon by a 20 N force. What is the acceleration of the object? 8. A drag racer is driving at a constant speed of 110 km/h. What is the force needed to keep the car in motion? 9. A 100 N force is acting on an 8 kg block. What is the acceleration of the block? 10. A 2 kg object is accelerated by a 4 N force. What is its acceleration?