# 5 Lecture

## PHY101

### Midterm & Final Term Short Notes

## Applications of Newton’s Laws – I

Newton’s laws of motion are fundamental concepts in physics that describe the behavior of objects in motion. They are the foundation of classical mechanics and have a wide range of applications in our daily lives.

**Important Mcq's**

Midterm & Finalterm Prepration

Past papers included

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**What external force is used to counteract the motion caused by wind and earthquakes in skyscrapers?**

A) Gravity

B) Friction

C) Dampers and braces

D) Electric fields

Answer: C) Dampers and braces

**Which law of motion is relevant in the sport of baseball?**

A) Newton's first law

B) Newton's second law

C) Newton's third law

D) None of the above

Answer: B) Newton's second law

**What principle is behind rocket propulsion?**

A) Newton's first law

B) Newton's second law

C) Newton's third law

D) None of the above

Answer: C) Newton's third law

**How do jet engines operate based on Newton's third law of motion?**

A) By expelling exhaust gases at low speed in one direction

B) By expelling exhaust gases at high speed in one direction

C) By attracting particles towards the engine

D) By rotating rapidly in the opposite direction

Answer: B) By expelling exhaust gases at high speed in one direction

**What is the significance of Newton's laws of motion in daily life?**

A) They have no significance in daily life

B) They are only relevant for scientists and engineers

C) They have a wide range of applications in daily life

D) They are only relevant in outer space

Answer: C) They have a wide range of applications in daily life

**What is the law of inertia?**

A) Newton's first law of motion

B) Newton's second law of motion

C) Newton's third law of motion

D) None of the above

Answer: A) Newton's first law of motion

**What is the force acting on an object equal to, according to Newton's second law of motion?**

A) Mass divided by acceleration

B) Acceleration divided by mass

C) Mass multiplied by acceleration

D) Velocity multiplied by time

Answer: C) Mass multiplied by acceleration

**What external force acts on passengers in a car during a sudden stop?**

A) Friction

B) Gravity

C) Seat belts

D) None of the above

Answer: C) Seat belts

**How is Newton's third law relevant in the launch of spacecraft?**

A) The force of gravity propels the spacecraft

B) The force of the exhaust gases propels the spacecraft

C) The force of electric fields propels the spacecraft

D) None of the above

Answer: B) The force of the exhaust gases propels the spacecraft

**How do engineers ensure the stability of skyscrapers?**

A) By applying external forces to the building

B) By increasing the mass of the building

C) By reducing the height of the building

D) By making the building wider at the base

Answer: A) By applying external forces to the building

**Subjective Short Notes**

Midterm & Finalterm Prepration

Past papers included

Download PDF
**What is Newton's first law of motion?**

**Answer: **Newton's first law of motion states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity unless acted upon by an external force.

**What is the law of inertia?**

**Answer: **The law of inertia is another name for Newton's first law of motion, which states that an object will resist changes in its state of motion.

**How do seat belts in cars demonstrate the first law of motion?**

**Answer: **Seat belts in cars provide an external force that acts on passengers, preventing them from moving forward and reducing the risk of injury in a sudden stop.

**What external forces are used to ensure the stability of skyscrapers?**

**Answer: **Engineers use external forces, such as dampers and braces, to counteract the motion caused by wind and earthquakes and ensure the stability of skyscrapers.

**What is Newton's second law of motion?**

**Answer: **Newton's second law of motion states that the force acting on an object is equal to its mass multiplied by its acceleration (F = ma).

**How is Newton's second law relevant in the sport of baseball?**

**Answer: **The force applied by a pitcher to a baseball is determined by the mass of the ball and the desired acceleration, as described by Newton's second law.

**What is the principle behind rocket propulsion?**

**Answer: **The principle behind rocket propulsion is Newton's third law of motion, which states that for every action, there is an equal and opposite reaction.

**How do jet engines operate based on Newton's third law of motion?**

**Answer: **Jet engines operate by expelling exhaust gases at high speed in one direction, which propels the aircraft in the opposite direction, in accordance with Newton's third law.

**How is Newton's third law relevant in the launch of spacecraft?**

**Answer:** The force of the exhaust gases expelled from the rocket engine propels the spacecraft in the opposite direction, in accordance with Newton's third law.

**What is the significance of Newton's laws of motion in daily life?**

**Answer:** Newton's laws of motion are fundamental concepts in physics that have a wide range of applications in our daily lives, from the design of safety devices to the construction of buildings and the operation of vehicles and machinery.

### Applications of Newton’s Laws – I

Isaac Newton’s laws of motion are fundamental concepts in physics that describe the behavior of objects in motion. They are the foundation of classical mechanics and have a wide range of applications in our daily lives. In this article, we will discuss the applications of Newton’s laws of motion, with a focus on the first law.**Newton’s first law of motion**states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity unless acted upon by an external force. This law is also known as the law of inertia, which means that an object will resist changes in its state of motion. One application of Newton’s first law is in the design of seat belts in cars. When a car suddenly stops, the passengers inside continue to move forward due to inertia. Without seat belts, the passengers would collide with the dashboard or windshield, causing serious injuries or even death. However, seat belts provide an external force that acts on the passengers, preventing them from moving forward and reducing the risk of injury. Another application of the first law is in the construction of skyscrapers. Buildings are designed to withstand the forces of wind and earthquakes, which can cause them to sway. However, the first law of motion states that an object in motion will remain in motion at a constant velocity unless acted upon by an external force. Therefore, engineers use external forces, such as dampers and braces, to counteract the motion caused by these forces and ensure the stability of the building.

**Newton’s second law of motion**is also important in many applications, which states that the force acting on an object is equal to its mass multiplied by its acceleration (F = ma). This law allows us to calculate the force required to move an object of a certain mass at a certain speed. One example of the second law is in the sport of baseball. The pitcher applies a force to the ball, accelerating it towards the batter. The faster the ball is thrown, the greater the force required. The mass of the ball is also a factor in determining the force needed, as a heavier ball requires more force to accelerate than a lighter one.

**The third law of motion,**which states that for every action, there is an equal and opposite reaction, is also relevant in many applications. One example is rocket propulsion, where the force of the exhaust gases expelled from the rocket engine propels the rocket in the opposite direction. This is also the principle behind the operation of jet engines and the launch of spacecraft.

**In conclusion,**Newton’s laws of motion have a wide range of applications in our daily lives, from the design of safety devices to the construction of buildings and the propulsion of spacecraft. The first law, in particular, highlights the importance of external forces in controlling the motion of objects and preventing them from colliding with other objects or losing stability. The second law allows us to calculate the force required to move objects of different masses at different speeds, while the third law describes the principle of action and reaction, which is fundamental in many areas of physics.