A force F = (cx - 3.00x^2) i^ acts on a virus as the virus moves along an x axis, with F measured in Newtons, x in meters, and c a constant. At x = 0, the virusâ€™s kinetic energy is 20.0 J, while at x = 3.00 m, it is 11.0 J. Find c.

Question

Physics

Brenna Jackson

4 March, 07:43

A force F = (cx - 3.00x^2) i^ acts on a virus as the virus moves along an x axis, with F measured in Newtons, x in meters, and c a constant. At x = 0, the virusâ€™s kinetic energy is 20.0 J, while at x = 3.00 m, it is 11.0 J. Find c.

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Answers (1)

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Amirah Nash · Answer 1

c = 4

Explanation:

From work-energy theorem KE = workdone.

Given F = (cx - 3.00x²) i

W = ∫Fdx = ∫ (cx - 3.00x²) dx = cx²/2 - 3.00x³/3 + A

W = cx²/2 - x³ + A

Where A is a constant

At x = 0, KE = 20J

So W = 20J at x = 0

20 = c*0 - 0 + A

A = 20

So W = cx²/2 - x³ + 20

Also when x = 3.00m, W = KE = 11J

So

11 = c*3²/2 - 3³ + 20

11 = 4.5c - 7

4.5c = 11 + 7

4.5c = 18

c = 18/4.5 = 4

c = 4