Mechanics

Question 1

What does ‘mechanics’ in physics study?

Answer 1

Mechanics deals with the behavior of physical bodies under forces or displacements, including statics, kinematics, and dynamics.

Question 2

State Newton’s First Law of Motion.

Answer 2

A body remains at rest or moves with constant velocity in a straight line unless acted upon by an external force.

Question 3

State Newton’s Second Law of Motion.

Answer 3

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass: F = m a.

Question 4

State Newton’s Third Law of Motion.

Answer 4

For every action force, there is an equal and opposite reaction force.

Question 5

What is the definition of kinematics?

Answer 5

Kinematics is the branch of mechanics that describes motion without considering forces that cause it.

Question 6

Differentiate between distance and displacement.

Answer 6

Distance is the total path length traveled; displacement is the straight-line change in position with direction.

Question 7

What is velocity?

Answer 7

Velocity is the rate of change of displacement with respect to time, including direction (v = Δs / Δt).

Question 8

What is acceleration?

Answer 8

Acceleration is the rate of change of velocity with respect to time (a = Δv / Δt).

Question 9

Give the equation for constant acceleration motion (SUVAT equation).

Answer 9

s = ut + ½at² (where s = displacement, u = initial velocity, a = constant acceleration, t = time).

Question 10

What is uniform circular motion?

Answer 10

Motion in a circle at constant speed, where velocity’s direction changes constantly, requiring a centripetal force.

Question 11

Define centripetal force.

Answer 11

The net inward force on an object moving in a circular path, given by F = mv² / r.

Question 12

What is inertia?

Answer 12

Inertia is the tendency of an object to resist changes to its state of motion (related to mass).

Question 13

How is momentum defined?

Answer 13

Momentum (p) is the product of an object’s mass and its velocity: p = m v.

Question 14

What is impulse and its relation to momentum?

Answer 14

Impulse is the change in momentum, calculated as Force × Time = Δp.

Question 15

State the principle of conservation of momentum.

Answer 15

In a closed system, the total momentum before an interaction equals the total momentum after the interaction.

Question 16

Define work in the context of mechanics.

Answer 16

Work (W) is done when a force causes displacement: W = F × d × cos(θ).

Question 17

How is energy defined?

Answer 17

Energy is the capacity to do work; it exists in various forms (kinetic, potential, thermal, etc.).

Question 18

Give the formula for kinetic energy.

Answer 18

Kinetic Energy (KE) = ½ m v².

Question 19

Give the formula for gravitational potential energy.

Answer 19

GPE = m g h, where g is gravitational acceleration and h is height above a reference.

Question 20

What is the definition of power in mechanics?

Answer 20

Power (P) is the rate of doing work: P = W / t or P = F v (for constant force and velocity).

Question 21

Explain what friction is.

Answer 21

Friction is a force opposing relative motion between two surfaces in contact.

Question 22

Differentiate between static friction and kinetic (sliding) friction.

Answer 22

Static friction acts when there is no relative motion; kinetic friction acts when surfaces are sliding past each other.

Question 23

What is the coefficient of friction?

Answer 23

A dimensionless number (μ) representing friction level between two surfaces; F_friction = μ × Normal Force.

Question 24

Define torque (moment of a force).

Answer 24

Torque = Force × Perpendicular distance from pivot, causing rotational motion.

Question 25

What is equilibrium in mechanics?

Answer 25

A state where the net force and net torque on a body are zero, so there’s no linear or rotational acceleration.

Question 26

What does ‘center of gravity’ mean?

Answer 26

The point at which an object’s entire weight can be considered to act for balancing and stability purposes.

Question 27

Explain the principle of moments.

Answer 27

For rotational equilibrium: Sum of clockwise moments = Sum of counterclockwise moments about a pivot.

Question 28

What is a simple machine?

Answer 28

A basic mechanical device (lever, pulley, inclined plane, screw, wheel & axle) that changes force magnitude or direction.

Question 29

Define mechanical advantage (MA).

Answer 29

MA = Load / Effort, or Output Force / Input Force, for a simple machine.

Question 30

Why is mechanical efficiency usually less than 100%?

Answer 30

Friction and other energy losses convert some input energy into heat or other non-useful forms.

Question 31

What is the difference between statics and dynamics?

Answer 31

Statics deals with forces in systems at rest (no acceleration), while dynamics studies forces and motion in accelerating systems.