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A particle experiences a variable force in a horizontal x-y plane. Assume distance in meters and force in newton. If the particle moves from point (1,2) to point (2,3) in the x-y plane, the Kinetic Energy changes by
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a
50 J
b
25.0 J
c
0 J
d
12.5 J
answer is C.
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Detailed Solution

A particle experiences a variable force f=4xi in a horizontal x-y plane. The particle is influenced by a force expressed as f=(4xi + 3y2j), which varies with position. To determine the change in kinetic energy as the particle moves from point (1, 2) to point (2, 3), we can use the work-energy theorem.
According to the work-energy theorem, the work done by the variable force is equal to the change in kinetic energy. Since a particle experiences a variable force f=4xi+3y2j, we can calculate the work done using the integral:
W = ∫ F ⋅ (dx i + dy j)
Substituting the given force f=(4xi + 3y2j) into the equation:
W = ∫12 4x dx + ∫23 3y2 dy
Solving each integral separately:
∫12 4x dx = [ 2x2 ]12 = (2 × 22) - (2 × 12) = 8 - 2 = 6
∫23 3y2 dy = [ y3 ]23 = (33) - (23) = 27 - 8 = 19
Adding both values, the total work done by the variable force f=4xi+3y2j is:
W = 6 + 19 = 25 J
Therefore, under the action of a variable force f 4xi 2yj, the kinetic energy of the particle changes by 25 J as it moves from point (1, 2) to point (2, 3).
This calculation shows how a particle experiences a variable force f=4xi in combination with a force term 3y2j, leading to a total kinetic energy change of 25 J. Understanding how a force f=(4xi + 3yj) affects the particle's motion is crucial in analyzing motion under varying conditions.