Physics Test 3 Flashcards
True or False: Two cars collide at an intersection, but do not “stick together” after the collision. Therefore, the collision was elastic.
False
True or False: An object at rest on a slick surface is struck by a second object. After the collision, both objects must be moving.
False
True or False: A system of particles with zero momentum must also have zero kinetic energy.
False
True or False: It is possible for two isolated objects to collide so that all the initial kinetic energy of the system is lost.
True
True or false: A system of particles with zero kinetic energy must also have zero momentum.
True
An appliance box has a square base with sides of length L, and has rectangular sides with a height of 2L. The top of the box is missing. The box is made from cardboard of uniform thickness and density. What is the height of the center of mass of this open box, with respect to the bottom of the box?
8L/9
It is predicted that gradual warming of the Earth over the next century will cause substantial portions of the Greenland and Antarctic ice sheets to melt. How will this affect the Earth’s moment of inertia?
How will this affect the amount of time in one day?
Earth’s moment of inertia will increase.
The day length will increase.
Consider the two rotating systems shown below. Each one consists of a small dense mass m attached to a rod of negligible mass and length L. The rod is pivoted about one end. In one of the systems, the mass is attached to the free end of the rod; in the other system, the mass is attached to the rod’s midpoint.
The rods are released from rest in the horizontal position at the same time. When the rod on the left reaches the vertical position, approximately where is the rod to the right?
C: past vertical
A playground merry-go-round spins about its axis with negligible friction. A child moves from the center of the merry-go-round to the rim. For this system, indicate which of the following quantities change.
Unchanged: Potential energy
Changed: Angular speed
Changed: Moment of inertia
Unchanged: Angular momentum
Changed: Rotational kinetic energy
Unchanged: Mass
Two rotating systems differ only in that the two spherical movable masses are positioned either far from the axis of rotation (left) or near the axis of rotation (right). Is the moment of inertia of the right greater than or smaller than the moment of inertia of the left
Smaller
Two rotating systems differ only in that the two spherical movable masses are positioned either far from the axis of rotation (left) or near the axis of rotation (right). If hanging blocks on the end of a spool in the center of the two hanging masses were dropped which would land first?
The one on the right because of the increase in angular speed
If you reduce the moment of inertia of a system by a factor of two the angular velocity would change to?
It would be multiplied by two
