Why is Newton's cradle an "almost-ideal" system?(1 point)

Question

Responses

The system would work more efficiently if more balls were added.
The system would work more efficiently if more balls were added.

The balls continue on for an unlimited amount of time.
The balls continue on for an unlimited amount of time.

Friction and air resistance are negligible and the system continues to move indefinitely.
Friction and air resistance are negligible and the system continues to move indefinitely.

Friction and air resistance cause the balls to slow down eventually and stop.
Friction and air resistance cause the balls to slow down eventually and stop.
Question 2
Which choice below is an example of a perfectly closed system?(1 point)
Responses

An automobile moving down the highway. Energy transfer only occurs inside the motor.
An automobile moving down the highway. Energy transfer only occurs inside the motor.

A cup of water with ice in it, open to the air.
A cup of water with ice in it, open to the air.

Newton's cradle. The energy transfer only occurs between the balls.
Newton's cradle. The energy transfer only occurs between the balls.

A cup of tea with a lid on it. energy transfer takes place with the cup and the surroundings, but no matter leaves the tea.

Answer 1

For the first question:

Friction and air resistance cause the balls to slow down eventually and stop.

This choice accurately describes why Newton's cradle is considered an "almost-ideal" system. In theory, without any external forces acting on it, the energy would be conserved indefinitely, but in reality, friction and air resistance will cause energy loss and the balls will eventually come to a stop.

For the second question:

A cup of tea with a lid on it. energy transfer takes place with the cup and the surroundings, but no matter leaves the tea.

While this option describes a system that minimizes matter exchange with the environment (which is a characteristic of a closed system), it is important to note that energy transfer, such as heat loss, may still occur. A truly "perfectly closed system" is one that would not allow any energy or matter to enter or leave; therefore, none of these options perfectly fits the definition of a "perfectly closed system," but the closest in context with minimal matter transfer while allowing energy exchange is the cup of tea with a lid.