Lesson 2 -Newtons 3 laws of Motion

• Who formulated the three laws of motion?

  Sir Isaac Newton
• What do Newton's three laws of motion describe?

  The relationship between an object and the forces acting upon it
• What are the three laws of motion formulated by Newton?

  1. The Law of Inertia 2. The Law of Acceleration 3. The Law of Action and Reaction
• What does the Law of Inertia state?

  An object at rest will remain at rest, and an object in motion will continue moving at a constant velocity unless acted upon by an unbalanced force
• How does the Law of Inertia apply to a ball rolling on a smooth surface?

  The ball will continue rolling at a constant speed until an unbalanced force, like friction, acts upon it
• What is the mathematical expression for the Law of Acceleration?

  F = ma
• If an object has a mass of 5 kg and a net force of 20 N is applied, what is its acceleration?

  $a =$$\frac{F}{m} =$$\frac{20 \text{ N}}{5 \text{ kg}} =$$4 \text{ m/s}^2$
• What does the Law of Action and Reaction state?


  For every action, there is an equal and opposite reaction
• If a person pushes against a wall with a force of 30 N, what force does the wall exert back on the person?

  30 N
• How does the Law of Action and Reaction apply when a person jumps off a boat?

  The person pushes off the boat, causing the boat to move in the opposite direction
• What are the implications of Newton's three laws of motion in classical mechanics?

  - They provide a framework for understanding motion - They apply to objects from small particles to celestial bodies - They help predict the behavior of objects under various forces
• What is the force exerted by the wall on a person who pushes it with a force of 50 Newtons according to the law of action and reaction?

  50 Newtons
• What does the law of action and reaction state?


  The law states that for every action, there is an equal and opposite reaction.
• What are examples of Newton's three laws of motion?

  1. **Law of Inertia**: - A ball at rest remains at rest until an unbalanced force acts on it. - A car continues moving at constant speed unless brakes are applied. 2. Law of Acceleration: - More force is needed to accelerate a heavy object than a lighter one. - A heavy box accelerates more slowly than a lighter box with the same force. 3. Law of Action and Reaction: - Jumping off a boat causes the boat to move in the opposite direction. - Kicking a ball results in an equal and opposite force on your foot.
• How does the law of inertia apply when you stop suddenly in a car?

  You feel pushed forward due to your body's inertia.
• Why is it easier to push a shopping cart when it's empty compared to when it's full?

  Because the heavier load requires more force to accelerate.
• What does the law of acceleration state?

  The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
• How does the law of action and reaction explain the motion of a satellite orbiting the Earth?

  The satellite is pulled towards the Earth by gravity, and the Earth exerts an equal and opposite force on the satellite.
• How does the law of inertia contribute to a satellite's motion?

  The law of inertia explains that the satellite continues to move in a circular orbit unless acted upon by an unbalanced force.
• What role does the law of acceleration play in satellite motion?

  The gravitational force causes the satellite to accelerate towards the Earth, maintaining its orbit.
• What is the law that explains why a car requires more force to accelerate from a standstill?

  The law of acceleration.
• What are the applications of Newton's laws of motion in various fields?

  1. **Mechanics and Engineering**: - Designing vehicles and structures. - Analyzing mechanical systems. 2. Sports and Athletics: - Analyzing athlete motion. - Designing sports equipment. 3. Astronomy and Astrophysics: - Describing celestial body motion. - Predicting spacecraft trajectories. 4. Everyday Life: - Explaining daily activities like walking and driving. - Designing safer products.
• Why is it easier to push a heavy object on a slippery surface compared to a rough surface?

  The law of inertia explains that less friction means less resistance to changing the object's state of motion.
• How do the law of inertia and the law of acceleration contribute to satellite motion?

  The law of inertia explains the satellite's constant motion, while the law of acceleration explains its circular acceleration due to gravity.
• What is the definition of work in physics?

  Work is a scalar quantity that represents the amount of energy transferred by a force acting on an object as it moves in the direction of that force.
• What are the requirements for work to be done?

  There must be a force acting on an object and the object must move in the direction of that force.
• What happens if the force and displacement are in opposite directions?

  No work is done if the force and displacement are in opposite directions.
• What is the formula for calculating work?

  Work (W) is calculated using the formula $W =$$F \cdot d \cdot \cos \theta$.
• What does the cosine term in the work formula account for?

  The cosine term accounts for the fact that work is only done when the force and displacement are in the same direction.
• What is kinetic energy?

  Kinetic energy (KE) is the energy of motion, given by the formula $KE =$$\frac{1}{2}m v^2$.
• What is the formula for potential energy in a gravitational field?

  Potential energy (PE) is given by the formula $PE =$$mgh$.
• How is work related to changes in energy?

  The amount of work done on an object is equal to the change in its total energy.
• How much work is done when a 2 kg object is lifted 5 m vertically against gravity?

  The work done is $W =$$mgh =$$2 \cdot 9.8 \cdot 5 =$$98\, \text{J}$.
• What is the relationship expressed by the formula $W =$$\Delta E$?


  Work done (W) is equal to the change in the object's total energy (ΔE).
• What is the definition of power in physics?

  Power is the rate at which work is done or energy is transferred.
• If the same 2 kg object is lifted 10 m instead of 5 m, how much work is done?

  The work done is $W =$$mgh =$$2 \cdot 9.8 \cdot 10 =$$196\, \text{J}$.
• What is the formula for calculating power?

  The formula for power is $P =$$\frac{W}{t}$.
• What is the power output when a person lifts a 20 kg object 5 meters in 2 seconds?


  The power output is $P =$$\frac{980}{2} =$$490\, \text{W}$.
• If the same 20 kg object is lifted 10 meters in 4 seconds, what is the power output?

  The power output is $P =$$\frac{1960}{4} =$$490\, \text{W}$.