Answer :
Answer:
6.875 m/s
Explanation:
The force is variable which is given by
F(x) = 18 - 0.53 x
mass of the box, m = 8.9 kg
initially it is at rest at x = 0
Let the velocity is v after travelling a distance of 15 m.
According to the work energy theorem, the work done by all the forces is equal to the change in kinetic energy of the body.
Work done = change in kinetic energy
[tex]\int \overrightarrow{F}.d\overrightarrow{x}=\Delta K.E[/tex]
[tex]\int_{0}^{15} \left ( 18-0.53 x \right )dx=\frac{1}{2}\times m \left ( v^{2}-u^{2} \right )[/tex]
[tex]\left ( 18x-0.265x^{2} \right )_{0}^{15}=\frac{1}{2}\times 8.9\times \left ( v^{2}-0^{2} \right )[/tex]
18 x 15 - 0.265 x 15 x 15 = 4.45 x v²
270 - 59.625 = 4.45 v²
v² = 47.275
v = 6.875 m/s
Thus, the final velocity of the box is 6.875 m/s.