Question 1

Which of the following best describes an interaction in physics?

Accepted Answer

A mutual influence between two objects that produces either a physical change or a change in motion.

Question 2

A ball is dropped from a certain height and accelerates downward. Which interaction is responsible for this acceleration, and is it attractive or repulsive?

Accepted Answer

The interaction is with the Earth and is attractive.

Question 3

During an elastic collision between two carts of different masses, which of the following statements is true?

Accepted Answer

The ratio of the x components of their accelerations is equal to the negative inverse of the ratio of their masses.

Question 4

In a totally inelastic collision between a small car and a heavy truck moving at equal speeds in opposite directions, which experiences the greater change in momentum?

Accepted Answer

Both experience the same magnitude of change in momentum.

Question 5

Which of the following is true about kinetic energy during an elastic collision?

Accepted Answer

Kinetic energy is conserved before and after the collision, but not during the interaction.

Question 6

What is potential energy, and how is it stored in a system?

Accepted Answer

Potential energy is the part of converted kinetic energy that is temporarily stored as internal energy in reversible changes of configuration.

Question 7

A ball is pressed down on a spring and released. As the ball rises, which energy conversions occur?

Accepted Answer

Elastic potential energy converts to kinetic energy, then to gravitational potential energy.

Question 8

Which of the following best describes energy dissipation in a physical process?

Accepted Answer

Part of the converted kinetic energy does not reappear after the process and is said to be dissipated, usually as thermal energy.

Question 9

Which of the following is an example of a nondissipative interaction?

Accepted Answer

A spring launching a cart on a frictionless surface.

Question 10

Which equation correctly expresses the conservation of energy for a closed system using the four energy categories?

Accepted Answer

$$\Delta K + \Delta U + \Delta E_s + \Delta E_{th} = 0$$

Question 11

Near Earth’s surface, what is the formula for the change in gravitational potential energy when an object of mass $$m$$ moves a vertical distance $$\Delta x$$?

Accepted Answer

$$\Delta U_G = mg\Delta x$$

Question 12

Which of the following is a characteristic of a dissipative interaction?

Accepted Answer

It is irreversible and involves an increase in thermal energy.

Question 13

Which of the following is NOT a fundamental interaction in the universe?

Accepted Answer

Frictional interaction

Question 14

Which fundamental interaction is primarily responsible for chemical and biological processes?

Accepted Answer

Electromagnetic

Question 15

Why can we often ignore electromagnetic interactions when studying the motion of most ordinary objects?

Accepted Answer

Because most ordinary matter is electrically neutral.

Question 16

If two objects of masses $$m_1$$ and $$m_2$$ interact, what is the relationship between the x components of their accelerations?

Accepted Answer

$$\frac{a_{1x}}{a_{2x}} = -\frac{m_2$}{m_1$}$$

Question 17

Which of the following best describes the path independence of potential energy changes in a nondissipative system?

Accepted Answer

The change in potential energy depends only on the initial and final positions.

Question 18

A hockey puck slides on ice and slows down due to friction. What happens to its kinetic energy?

Accepted Answer

It is converted to thermal energy.

Question 19

Which of the following is true for a closed system undergoing a nondissipative interaction?

Accepted Answer

Mechanical energy is conserved: $$\Delta E_{mech} = 0$$

Question 20

Which of the following is a long-range interaction?

Accepted Answer

Magnetic force between two magnets.

Chapter 7: Interactions – Principles and Practice of Physics

Guida di studio - Domande di pratica

Study guide - Flashcard