The correct answer is -40 J. Explanation & Key Takeaways: • Work done (W) is calculated using the formula W = F × d × cos(θ), where F is force, d is displacement, and θ is the angle between force and displacement. • In this scenario, the force (F) is 20 N and the displacement (d) is 2 meters. • The angle (θ) between the force and the displacement is 180 degrees because the force acts in the direction opposite to the displacement. • The cosine of 180 degrees is -1, so W = 20 N × 2 m × cos(180°) = 20 × 2 × (-1) = -40 J. • Thus, the work done by the force is -40 joules. Related Concepts: • Work • In physics, work is defined as the transfer of energy that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement. • It is measured in joules (J) in the International System of Units (SI). • Force • Force is any interaction that, when unopposed, will change the motion of an object. • It is measured in newtons (N) in the SI system. • Displacement • Displacement is a vector quantity that refers to the change in position of an object. • It has both magnitude and direction and is measured in meters (m) in the SI system. • Angle Between Force and Displacement • The work done by a force is dependent on the angle between the force and the direction of displacement. • If the force and displacement are in the same direction, the angle is 0 degrees; if they are in opposite directions, the angle is 180 degrees.