An object is moving in a circular path with constant speed. Which of the following remains constant?
A. Acceleration
B. Linear momentum
C. Kinetic energy
D. Velocity
Answer: Option C
Solution (By JKExamLibrary)
Speed constant implies magnitude of velocity constant, so kinetic energy (½mv²) is constant. Velocity changes due to direction change. Acceleration (centripetal) is directed towards centre, changes direction. Linear momentum vector changes. So only kinetic energy remains constant.
Explanation:
Surface tension is defined as Force per unit length (F/L). Dimensional formula: [MLT⁻²] / [L] = [MT⁻²]. A spring constant (k) is defined by Hooke's Law as Force per unit extension (F/x), which also has dimensions [MLT⁻²] / [L] = [MT⁻²]. Thus, both share the same dimensional formula.
Assertion (A): When ice floats in water, its approximately 1/10th volume remains outside the water. Reason (R): The density of ice is approximately 10% less than the density of water.
A.Both A and R are true and R is the correct explanation of A.
B.A is true but R is false.
C.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
The density of ice is about 900 kg/m³ (0.9 g/cm³), while pure water is 1000 kg/m³ (1.0 g/cm³). According to the principle of floatation, the fraction of volume submerged is the ratio of densities: ρ_ice / ρ_water = 0.9. This means 90% is submerged, leaving exactly 10% (1/10th) exposed above the surface. Reason R explains Assertion A.
Explanation:
Fuse wire must melt easily (low melting point) to break circuit on overload, and have high resistance to produce sufficient heat (I²R). Materials: tin-lead alloy. Copper not used as fuse.
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