Question
A steel ball has a mass of 4.0 kg and rolls along a smooth, level surface at 62m/s. What is its kinetic energy. At first the ball was at rest on the surface. A force acted on it through a distance of 22 m to give it the speed of 62 m/s. What was the magnitude of the force?
Answers
drwls
Since it is rolling you must consider both the kinetic energy of both translation (forward motion) and rotation. The rotational kinetic energy is (1/2) I w^2 where I = (2/5) M R^2 for a solid sphere, and w = V/R is the angular velocity.
Put it all together and you find that the kinetic energy is (7/10)M V^2
Divide that by the distance of 22m over which the force acted, and you get the average force.
Put it all together and you find that the kinetic energy is (7/10)M V^2
Divide that by the distance of 22m over which the force acted, and you get the average force.