A constant force acting on a body of mass 5 kg changes its speed from 2 m/s to 8 m/s in 10 s. The magnitude of force is MCQ with Answer and Explanation
A constant force acting on a body of mass 5 kg changes its speed from 2 m/s to 8 m/s in 10 s. The magnitude of force is
A. 1 N
B. 5 N
C. 3 N
D. 0.5 N
Answer: Option C
Solution (By JKSSB Mock Tests)
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.
Explanation:
Q = mcΔθ = 2 × 4200 × 10 = 84,000 J = 84 kJ. Large specific heat of water makes it useful for cooling and climate moderation. Always check units: mass kg, c J/kg°C, ΔT °C.
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