26. An object starts at rest and is subjected to a force over distance of 7.00 m. After the object is free of the above force, a 224 N force can turn the object through a 90 corner of 0.250 m radius. How great was the initial force?

27. A model train car is coasting (no driving force) on a circular track. Initially the centripetal force necessary to keep the car going around the track is 5.00 N. If after the car has gone halfway around the circle the necessary centripetal force has been reduced to 1.86 N, what force of friction must be acting on the car?

28. A model railway train is on a circular track. The force of friction is 5.60N. The train started at rest and was driven by a force of 10.0 N for a distance of 45.4 cm. The driving force was then reduced and held at a constant 5.6 N. The centripetal force that must be provided by the track is 2.00 N. Calculate the circumference of the track.

The answers to the questions are:

26. 4.00N

27. 0.500N

28. 12.6m

What are the steps to solve each question?