PHYSICS · Multi-part · AP · Physics C: Mechanics · Work Energy and Power · Work Energy and Power
Problem
A pendulum bob of mass 0.25kg is suspended by a light, inextensible string of length 1.0m. The bob is pulled aside so that the string makes an angle corresponding to a vertical rise of 8.0cm of the bob and is then released from rest. Assume the motion is frictionless and take g=9.8ms−2.
(i) Write the expression for the gravitational potential energy of the bob at the highest point of release with reference to the lowest point of the swing.
(ii) Calculate this potential energy.
(iii) Using the principle of conservation of mechanical energy, find the speed of the bob as it passes through the lowest point.
(iv) Determine the kinetic and potential energies of the bob when the string makes an angle corresponding to a vertical rise of 4.0cm above the lowest point.
(v) Show that the total mechanical energy of the bob remains the same at all the three positions considered above.