Govt. Exams
Entrance Exams
For constant velocity, acceleration = 0. By Newton's first law, net force = 0. Therefore, friction force must equal applied force = 50 N.
An inertial frame has zero acceleration. A rotating frame undergoes centripetal acceleration, making it non-inertial. All others have constant velocity (zero acceleration).
Using s = ut + ½at², where u = 0, s = 100 m, t = 10 s. Therefore, 100 = 0 + ½a(100), giving a = 2 m/s²
Using v = u + at: 20 = 10 + a(5), a = 2 m/s². F = ma = 2×2 = 4 N
Using v = u + at: 0 = 20 + a(5), a = -4 m/s². Deceleration = 4 m/s²
By conservation of energy and kinematics, the stone returns with the same speed but opposite direction: 30 m/s downward
Using s = ut + ½at², where u = 0, a = 5 m/s², t = 6s: s = 0 + ½(5)(36) = 90 m
Newton's first law states that an object at rest remains at rest unless acted upon by an external force - this is the law of inertia.
Vertical component = F sin(60°) = 50 × (√3/2) = 50 × 0.866 = 43.3 N
Mass is a scalar quantity as it has magnitude only, not direction. Displacement, velocity, and acceleration are vectors.
