Unit 1- Mechanics and Materials

Question 1

What are the equations of motion for constant acceleration?

Answer 1

v=u+at, s=ut+ 0.5at^2, v^2=u^2+2as and s=(u+v)/2t.
Where u is initial velocity, v is final velocity, a is acceleration, t is time and s is displacement.

Question 2

Define displacement and how it differs from distance

Answer 2

Displacement is the shortest distance from the initial to the final position in a specific direction, while distance is the total path traveled without regard to direction.

Question 3

What is the significance of the area under a velocity-time graph?

Answer 3

The area under a velocity-time graph represents the displacement of an object.

Question 4

State Newton’s First Law of Motion

Answer 4

It states that an object remains at rest or in uniform motion unless acted upon by an external force.

Question 5

State Newton’s Second Law of Motion

Answer 5

The rate of change of momentum of an object is proportional to the applied force (f=ma)

Question 6

State Newton’s Third Law of Motion

Answer 6

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

Question 7

What is meant by the term resultant force?

Answer 7

The resultant force is the single force that has the same effect as all the forces acting on an object combined.

Question 8

Define the conditions required for an object to be at equilibrium

Answer 8

The sum of all forces acting on the object must be zero (ΣF=0), and the sum of all moments about any point must also be zero (ΣM=0)

Question 9

What is the formula for work done on an object?

Answer 9

Work = Force × Distance × cos(θ), where θ is the angle between the force and displacement direction.

Question 10

How is Kinetic Energy calculated?

Answer 10

KE= 1/2mv^2, where m is mass and v is velocity

Question 11

Define power.

Answer 11

Power is the rate at which work is done or energy is transferred.

Question 12

Give the formula for power in terms of energy transfer.

Answer 12

P=E/t, where E is energy and t is time.

Question 13

State the principle of conservation of energy.

Answer 13

Energy cannot be created or destroyed; it can only be transformed from one form to another, with the total energy in a closed system remaining constant.

Question 14

Define momentum.

Answer 14

Momentum is the product of an object’s mass and velocity.

Question 15

Provide the formula for momentum.

Answer 15

p=mv

Question 16

Explain the difference between elastic and inelastic collisions

Answer 16

In elastic collisions, both momentum and kinetic energy are conserved. In inelastic collisions, momentum is conserved, but kinetic energy is not.

Question 17

How is impulse related to momentum?

Answer 17

Impulse is the change in momentum of an object.

Question 18

What is the formula for impulse?

Answer 18

FΔt=Δp

Question 19

Define Stress

Answer 19

Stress is force per unit area

Question 20

Give the formula for stress

Answer 20

(𝜎=f/a)

Question 21

What is strain?

Answer 21

Strain is extension per unit length.

Question 22

Give the formula for strain.

Answer 22

(𝜖=ΔL/L)

Question 23

What does Young’s Modulus measure?

Answer 23

Young’s Modulus measures a material’s stiffness, calculated as the ratio of stress to strain.

Question 24

What is the formula for Young’s Modulus?

Answer 24

E=σ/ϵ

Question 25

How is the elastic limit of a material identified on a stress strain graph?

Answer 25

It is the point beyond which the material will no longer return to its original shape when the stress is removed.

Question 26

What is the difference between brittle and ductile materials?

Answer 26

Brittle materials break without significant deformation (e.g., glass), while ductile materials can be stretched into a wire before breaking (e.g., copper).

Question 27

Explain what is meant by tensile strength.

Answer 27

Tensile strength is the maximum stress a material can withstand while being stretched before breaking.

Question 28

What is Hooke's Law and how is it applied?

Answer 28

Hooke’s Law states that the force applied to a spring is directly proportional to the extension, provided the elastic limit is not exceeded

Question 29

What is the formula for Hooke's Law?

Answer 29

(F=kx)

Question 30

How is the density of a material calculated?

Answer 30

density=mass/volume

Question 31

Why do objects with the same volume but different masses have different densities?

Answer 31

Because density depends on both mass and volume; an object with greater mass in the same volume will have a higher density.

Question 32

Define viscosity

Answer 32

Viscosity is a fluid’s resistance to flow.

Question 33

How does viscosity affect motion of objects through a fluid?

Answer 33

higher viscosity means greater resistance to motion (e.g., honey vs. water).

Question 34

State Stoke's Law.

Answer 34

Stokes’ Law is the Drag Force (F)=6πηrv, where η is viscosity, r is radius of the object and v is velocity. It is used to calculate drag on small spherical objects moving through a viscous fluid.