Laws of Motion - Practice Flashcards

Flashcards covering the fundamental concepts of Newton's laws of motion, inertia, momentum, torque, and universal gravitation as described in the lecture notes.

What is the branch of physics that deals with the effect of force on bodies?

Mechanics, which is divided into statics and dynamics.

Distinguish between Kinematics and Kinetics.

Kinematics deals with the motion of bodies without considering the cause of motion, while Kinetics deals with the motion of bodies considering the cause of motion.

What did Aristotle define as 'natural motion'?

The concept that a moving body naturally comes to rest without any external influence of force.

According to Galileo, how do bodies of different mass behave when dropped in a vacuum?

Bodies of different size, shape, and mass fall at the same rate and reach the ground at the same time.

What is the scientific definition of 'Inertia'?

The inherent property of a body to resist any change in its state of rest or the state of uniform motion, unless it is influenced upon by an external unbalanced force.

Identify the three types of inertia.

Inertia of rest, inertia of motion, and inertia of direction.

What physical quantity identifies the impact of a force and is calculated as the product of mass and velocity?

Linear momentum, expressed as $p = mv$.

What are the SI and C.G.S. units of momentum?

The SI unit is $kg\,m\,s^{-1}$ and the C.G.S. unit is $g\,cm\,s^{-1}$.

State Newton's First Law of Motion.

Every body continues to be in its state of rest or the state of uniform motion along a straight line unless it is acted upon by some external force.

Define 'Like parallel forces'.

Two or more forces of equal or unequal magnitude acting along the same direction, parallel to each other.

What is an 'Equilibrant'?

A force that is equal to the resultant force in magnitude but opposite in direction, which brings a system to equilibrium.

Define 'Torque' ($\tau$) and its SI unit.

The rotating or turning effect of a force about a fixed point or axis, calculated as $\tau = F \times d$, with the SI unit $Nm$.

What constitutes a 'Couple' in mechanics?

Two equal and unlike parallel forces applied simultaneously at two distinct points whose line of action does not coincide.

What is the principle of moments for a body in equilibrium?

The algebraic sum of the moments in the clockwise direction is equal to the algebraic sum of the moments in the anticlockwise direction ($F_1 \times d_1 = F_2 \times d_2$).

State Newton's Second Law of Motion.

The force acting on a body is directly proportional to the rate of change of linear momentum of the body and the change in momentum takes place in the direction of the force ($F = ma$).

How is 1 Newton ($N$) defined?

The amount of force required for a body of mass $1\,kg$ to produce an acceleration of $1\,m/s^2$, where $1\,N = 10^5\,\text{dyne}$.

What is 'Impulse' ($J$) and how is it calculated?

Impulse is a large force acting for a very short interval of time, calculated as the product of force and time ($J = F \times t$), which equals the change in momentum.

State Newton's Third Law of Motion.

For every action, there is an equal and opposite reaction, and they always act on two different bodies ($F_B = -F_A$).

What formula represents Newton's universal law of gravitation?

$$F = \frac{G m_1 m_2}{r^2}$$

What is the value of the universal gravitational constant ($G$)?

$$6.674 \times 10^{-11}\,Nm^2\,kg^{-2}$$

What is the mean value of acceleration due to gravity ($g$) on the surface of the Earth?

$$9.8\,m/s^{2}$$

What is the mass of the Earth ($M$)?

$$5.972 \times 10^{24}\,kg$$

How does the value of $g$ vary across the Earth's surface?

The value of $g$ is maximum in the polar region and minimum in the equatorial region; it reduces as you move to higher altitudes or deeper below the surface.

Define Mass and Weight.

Mass is the quantity of matter in a body ($kg$), while weight is the gravitational force exerted on a body ($W = mg$).

What is the acceleration due to gravity on the surface of the Moon?

$1.625\,m/s^{2}$, which is about $0.1654$ times that of the Earth.

Explain the state of 'weightlessness'.

It refers to the state where the apparent weight of a body is zero ($R = 0$), occurring during free fall when acceleration ($a$) equals acceleration due to gravity ($g$).