core 5 - p4 Flashcards
(24 cards)
Define coplanar forces and provide an example.
Forces acting in the same plane. Example: A book resting on a table with gravity and normal force both in the vertical plane.
Convert 15 pounds (lbs) to kilograms (1 lb ≈ 0.4536 kg).
15×0.4536=6.804kg.
What is Poisson’s ratio?
The ratio of transverse strain to axial strain: ν = − ϵ transverse / ϵ axial .
Calculate the torque if a 50 N force is applied perpendicularly at 0.4 m from a pivot.
τ=r×F=0.4×50=20Nm.
τ=r×F=0.4×50=20Nm.
A1 v1 = A2 v2, where A = cross-sectional area and v = flow velocity.
Define sensible heat vs. latent heat.
Sensible heat: Heat causing temperature change (Q=mcΔT).
Latent heat: Heat causing phase change without temperature change (Q=mL).
A beam with a UDL of 200 N/m spans 5 m. Calculate the total load.
Total load = 200×5=1000N.
What is the Young’s modulus of steel (typical value)?
200 GPa (200×10 ^ 9 Pa).
State Charles’s Law and its formula.
“Volume of a gas is directly proportional to its temperature (in Kelvin) at constant pressure.”
Formula: V1 / T1 = V2 / T2
What is the purpose of a micrometer?
To measure small dimensions (e.g., thickness of a wire) with high precision (up to
±
0.01
mm
±0.01mm).
To measure small dimensions (e.g., thickness of a wire) with high precision (up to
±
0.01
mm
±0.01mm).
2.5×3.785=9.46L.
Define shear stress and its formula
Stress parallel to the material’s cross-section. Formula: τ = F / A, where F = force, A = area.
What is a hypothesis in the scientific method?
A testable prediction explaining a phenomenon, e.g., “Increasing temperature increases metal expansion.”
Calculate the stress on a 0.02 m² area under a 5000 N force.
Stress=
5000 / 0.02 = 250,000Pa (250 kPa).
What is absolute zero in thermodynamics?
0K (-273.15°C), the lowest possible temperature where molecular motion ceases.
Explain Hooke’s Law and its limit.
“Stress ∝ strain within the elastic limit.” Beyond this, material deformation becomes permanent
Convert 250 kPa to bar (1 bar = 100 kPa).
250 / 100 = 2.5bar.
What is the bending moment in a beam?
The internal moment causing a beam to bend, calculated as M=F×d (force × distance).
Define laminar flow vs. turbulent flow.
-Laminar: Smooth, layered fluid motion.
-Turbulent: Chaotic, irregular fluid motion.
What is gauge pressure?
Pressure measured relative to atmospheric pressure: P gauge = P absolute − P atm
A gas at 300 K occupies 10 L. What volume does it occupy at 450 K (constant pressure)?
Using Charles’s Law:
10 / 300 = V2 / 450 → V2 = 15L.
What is the principle of a hydraulic press?
Uses Pascal’s Law: P1 = P2 → F1 A1 = F2 A2. Small force on a small area amplifies force on a larger area.
Define strain and its formula.
Deformation per unit length. Formula: ϵ = ΔL / L
What is the SI unit of luminous intensity
Candela (cd).
