An object of mass 8 kg starts to move from rest under the action of a variable force F = 3 x N where x is the distance (in m ) covered by the object. If initially, the position of the object is x = 2 m , then find its speed (in m s - 1 ) when it crosses x = 10 m .

Question

An object of mass 8 kg starts to move from rest under the action of a variable force F = 3 x N where x is the distance (in m ) covered by the object. If initially, the position of the object is x = 2 m , then find its speed (in m s - 1 ) when it crosses x = 10 m .,

MARKS App · Accepted Answer

Increment in kinetic energy = work done 1 2 m v 2 - u 2 = ∫ x 1 x 2 F . d x = ∫ 2 10 3 x d x 1 2 m v 2 = 3 2 x 2 2 10 = 3 2 100 - 4 1 2 × 8 × v 2 = 3 2 × 96 v = 6 m s - 1

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