Pendulums

Pendulums

• Gizmo – Energy of a Pendulum• Complete Pendulum handout

Pendulums

What affects the period of a pendulum?

PendulumsHow does the kinetic energy and Potential energy relate to the motion of a pendulum?

How is the total mechanical energy of a pendulum affected by the changes in kinetic and potential energy?

Pendulums1. A simple pendulum consists of a bob of mass 0.085 kg attached to a string of length 1.5 m. The pendulum is raised to point Q, which is 0.08 m above its lowest position, and released so that it oscillates with small amplitude ϴ between the points P and Q as shown below.

(a) On the figures below, draw free-body diagrams showing and labeling the forces acting on the bob in each of the situations described.i. When it is at point P ii. When it is in motion at

its lowest position

Pendulums(b) Calculate the speed v of the bob at its lowest position.

(c) Calculate the force on tension in the string

(d) Describe one modification that could be made to double the period of

oscillation.

2. A 2-kg block initially hangs at rest at the end of two 1-meter strings of negligible mass as shown on the left diagram above. A 0.003-kg bullet, moving horizontally with a speed of 1000 m/s, strikes the block and becomes embedded in it. After the collision, the bullet/ block combination swings upward, but does not rotate. a. Calculate the speed v of the bullet/ block combination just after the collision. b. Calculate the ratio of the initial kinetic energy of the bullet to the kinetic energy of the bullet/ block combination immediately

after the collision. c. Calculate the maximum vertical height above the initial rest position reached by the bullet/block combination.