SCE Engineering Sciences 1 â Questions and Answers
Question 1: What is Newton's second law of motion?
- F = ma (force equals mass times acceleration) (Correct answer)
- Every action has an equal and opposite reaction
- An object at rest stays at rest
- Energy cannot be created or destroyed
Correct answer: F = ma (force equals mass times acceleration)
Newton's second law states that the net force acting on an object equals its mass multiplied by its acceleration (F = ma), forming the foundation of dynamics.
Question 2: The coefficient of thermal expansion is a measure of:
- How much a material expands per degree of temperature change (Correct answer)
- The heat capacity of a material
- The thermal conductivity of a material
- The melting point of a material
Correct answer: How much a material expands per degree of temperature change
The coefficient of thermal expansion (α) quantifies the fractional change in length, area, or volume per unit temperature change, critical for designing structures in Saudi Arabia's extreme temperatures.
Question 3: Hooke's Law states that stress is proportional to strain within the:
- Elastic limit (Correct answer)
- Plastic region
- Ultimate strength
- Fracture point
Correct answer: Elastic limit
Hooke's Law (Ï = Eε) applies only within the elastic region where deformation is reversible. Beyond the elastic limit, permanent plastic deformation occurs.
Question 4: The first law of thermodynamics is a statement of:
- Conservation of energy (Correct answer)
- Conservation of momentum
- Conservation of mass
- Entropy increase
Correct answer: Conservation of energy
The first law states that energy cannot be created or destroyed, only converted between forms. For a closed system, ÎU = Q - W (internal energy change equals heat added minus work done).
Question 5: Young's modulus is defined as the ratio of:
- Stress to strain in the elastic region (Correct answer)
- Force to displacement
- Strain to stress
- Load to area
Correct answer: Stress to strain in the elastic region
Young's modulus (E) = stress/strain = (F/A)/(ÎL/L) in the elastic region. It measures a material's stiffness. Steel has E â 200 GPa, concrete â 25-30 GPa.
Question 6: In fluid mechanics, Reynolds number determines:
- Whether flow is laminar or turbulent (Correct answer)
- The fluid pressure
- The fluid temperature
- The fluid density
Correct answer: Whether flow is laminar or turbulent
Reynolds number (Re = ÏvD/ÎŒ) is a dimensionless ratio of inertial to viscous forces. Re < 2300 typically indicates laminar flow, while Re > 4000 indicates turbulent flow in pipes.
SCE Engineering Sciences 1
What is Newton's second law of motion?