To calculate the work done by the force, we can use the formula:
Work = Force x Distance x cos(theta)
where force is the applied force, distance is the displacement of the object, and theta is the angle between the force and displacement vectors.
However, we don't have the force or distance in this problem. But we can use the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy:
Work = ΔKE = KEf - KEi
where ΔKE is the change in kinetic energy, KEf is the final kinetic energy, and KEi is the initial kinetic energy.
We can find the initial and final kinetic energies using the formula:
KE = 1/2 * m * v^2
where m is the mass of the object and v is its velocity.
Initial KE = 1/2 * 20 kg * (5 m/s)^2 = 250 J
Final KE = 1/2 * 20 kg * (2 m/s)^2 = 40 J
ΔKE = Final KE - Initial KE = 40 J - 250 J = -210 J
Since the kinetic energy decreased, the work done on the object must be negative, indicating that the force is acting opposite to the direction of motion. Therefore, the work done by the force is:
Work = ΔKE = -210 J
So, the work done by the force is -210 J.