# 8 Lecture

## PHY101

### Midterm & Final Term Short Notes

## Momentum

Momentum is a fundamental concept in physics that describes the quantity of motion possessed by an object. It is defined as the product of an object's mass and its velocity.

**Important Mcq's**

Midterm & Finalterm Prepration

Past papers included

Download PDF
**Which of the following is the correct formula for momentum?**

A) P = mv

B) P = ma

C) P = Fnet

D) P = KE

Answer: A

**A 5 kg object is moving with a velocity of 10 m/s. What is its momentum?**

A) 10 kg m/s

B) 20 kg m/s

C) 50 kg m/s

D) 100 kg m/s

Answer: B

**What is the unit of momentum?**

A) kg

B) m/s

C) N

D) kg m/s

Answer: D

**Which of the following is an example of an inelastic collision?**

A) Two pool balls colliding and bouncing off each other

B) A ball being dropped from a height and bouncing back up

C) A car colliding with a wall and coming to a stop

D) A rocket accelerating in space

Answer: C

**If the net force acting on an object is zero, what happens to its momentum?**

A) It increases

B) It decreases

C) It remains constant

D) It becomes negative

Answer: C

**According to the law of conservation of momentum, in a closed system, what happens to the total momentum before and after a collision?**

A) It decreases

B) It increases

C) It remains constant

D) It becomes negative

Answer: C

**Which of the following is an example of an isolated system?**

A) A moving car

B) A tennis ball being hit by a racquet

C) A rocket launching into space

D) A stationary block on a table

Answer: D

**What is the relationship between impulse and momentum?**

A) Impulse is equal to the change in momentum

B) Impulse is equal to the initial momentum

C) Impulse is equal to the final momentum

D) Impulse is not related to momentum

Answer: A

**What is the difference between elastic and inelastic collisions?**

A) Elastic collisions conserve kinetic energy, while inelastic collisions do not

B) Elastic collisions result in objects sticking together, while inelastic collisions result in objects bouncing off each other

C) Elastic collisions result in a change in momentum, while inelastic collisions do not

D) Elastic collisions are only possible in space, while inelastic collisions occur on Earth

Answer: A

**Two objects with masses of 2 kg and 4 kg, respectively, are moving towards each other with velocities of 3 m/s and -2 m/s. What is the total momentum of the system?**

A) 2 kg m/s

B) -2 kg m/s

C) 6 kg m/s

D) -6 kg m/s

Answer: B

**Subjective Short Notes**

Midterm & Finalterm Prepration

Past papers included

Download PDF
**Define momentum in physics.**

**Answer:** Momentum is a physical quantity that describes an object's motion. It is the product of an object's mass and velocity. The momentum of an object is a vector quantity, meaning it has both magnitude and direction.

**What is the formula for momentum?**

**Answer:** The formula for momentum is momentum = mass x velocity, which can be expressed as p = mv.

**What is the principle of conservation of momentum?**

**Answer:** The principle of conservation of momentum states that the total momentum of a system of objects remains constant if no external forces act on the system.

**What is the difference between elastic and inelastic collisions?**

**Answer:** In an elastic collision, both the total momentum and kinetic energy of the system are conserved, while in an inelastic collision, only the total momentum is conserved.

**What is impulse?**

**Answer: **Impulse is the change in momentum of an object resulting from an applied force. It is equal to the force multiplied by the time during which it acts.

**What is the relationship between force, time, and impulse?**

**Answer: **The impulse of a force is equal to the product of the force and the time during which it acts. This can be expressed as J = Ft.

**What is the difference between linear momentum and angular momentum?**

**Answer: **Linear momentum is the product of an object's mass and velocity, while angular momentum is the product of an object's moment of inertia and angular velocity.

**What is the law of conservation of angular momentum?**

**Answer: **The law of conservation of angular momentum states that the total angular momentum of a system remains constant if no external torques act on the system.

**How is momentum used in real-world applications?**

**Answer:** Momentum is used in a variety of real-world applications, such as in the design of car safety features, the understanding of fluid dynamics, and the development of rocket propulsion systems.

**How can momentum be used to solve problems in physics?**

**Answer: **Momentum can be used to solve a wide range of problems in physics, such as collisions, motion in a gravitational field, and fluid flow. It provides a useful tool for analyzing the behavior of objects and systems in motion.

### What is Momentum?

Momentum is a fundamental concept in physics that describes the quantity of motion possessed by an object. It is defined as the product of an object's mass and its velocity. The concept of momentum is crucial in the understanding of various physical phenomena such as collisions, explosions, and the motion of objects under the influence of forces.#### The formula for momentum is given by:

#### p = mv

Where p is momentum, m is the mass of the object, and v is its velocity. The SI unit for momentum is kilogram-meter per second (kg?m/s). One of the fundamental principles of physics is the conservation of momentum, which states that the total momentum of a system of objects remains constant if no external forces act on the system. This principle can be observed in various physical phenomena such as collisions, where the total momentum of the colliding objects is conserved. Momentum is a vector quantity, which means it has both magnitude and direction. The direction of momentum is the same as that of the velocity vector. If an object is moving in the positive x-direction with a velocity v, its momentum in the x-direction is given by p = mv. If the object is moving in the opposite direction, its momentum in the x-direction is given by p = -mv.#### The principle of conservation of momentum can be expressed mathematically as:

#### ?p1 = ?p2

Where ?p1 is the initial total momentum of the system and ?p2 is the final total momentum of the system. This principle can be used to solve various problems in physics, such as determining the velocities of objects after a collision. In addition to being a fundamental concept in physics, momentum also has practical applications. For example, in the design of safety features in vehicles, the principles of momentum and energy are used to minimize the force of impact in the event of a collision. This is achieved by increasing the time of impact, which reduces the force of the collision. Another practical application of momentum is in rocket propulsion. Rockets work on the principle of conservation of momentum, where the momentum of the exhaust gases expelled from the rocket is equal and opposite to the momentum of the rocket itself. This allows the rocket to propel itself forward in space. The concept of momentum is also important in the understanding of the behavior of fluids, such as air and water. In fluid mechanics, the principle of conservation of momentum is used to explain the motion of fluids and the forces exerted by them on objects.**In conclusion,**momentum is a fundamental concept in physics that describes the quantity of motion possessed by an object. It is defined as the product of an object's mass and its velocity and is conserved in the absence of external forces. The principle of conservation of momentum has practical applications in various fields such as vehicle design, rocket propulsion, and fluid mechanics. Understanding the concept of momentum is essential for a thorough understanding of physics and its practical applications.