The instrument used to measure pressure difference is MCQ with Answer and Explanation

Explanation:
Gravitational force acts vertically downward. For horizontal displacement, the angle between force and displacement is 90°, so work W = F·d·cos90° = 0. Gravity does no work for horizontal motion; it only does work for vertical displacement components. Memory aid: 'Work = F d cosθ; θ=90° ⇒ W=0'.

Explanation:
For equilibrium, net force = 0. If forces F₁ and F₂ are perpendicular, their vector sum R = √(F₁² + F₂²). The third force F₃ must balance R, so F₃ = -R, i.e., equal in magnitude and opposite in direction to the vector sum of F₁ and F₂. Memory aid: 'Equilibrium: vector sum of all forces = 0; third force closes the triangle'. This statics concept is frequently tested in competitive exams. Always use vector addition for force equilibrium; scalar sum is incorrect for non-collinear forces.

Explanation:
Acceleration a = (v-u)/t = (8-2)/10 = 0.6 m/s². Force F = m×a = 5 × 0.6 = 3 N. Alternatively, impulse = change in momentum = 5×(8-2) = 30 kg m/s, time = 10 s, so average force = 30/10 = 3 N. Always check direction, but magnitude is 3 N.