A sled with mass 11.00 kg moves in a straight line on a frictionless horizontal surface. At one point in its path, its speed is 4.00 m/s; after it has traveled a distance 3.00 m beyond this point, its speed is 7.00 m/s. Use the work-energy theorem to find the force acting on the sled, assuming that this force is constant and that it acts in the direction of the sled's motion.

The magnitude of the force acting on the sled is 60.5 newtons.

Explanation:

The Work-Energy Theorem states that the work done by the external force applied on the sled (), in joules, is equal to the change of its translational kinetic energy (), in joules:

(1)

By definitions of work and translational kinetic energy we expand the equation above:

(1b)

Where:

- External force applied on the sled, in newtons.

- Travelled distance, in meters.

- Initial and final velocities, in meters per second.

If we know that , , and , then the external force applied on the sled is:

The magnitude of the force acting on the sled is 60.5 newtons.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.