Fundamental Physics Principles: Questions and Solutions

Physics Fundamentals: Multiple Choice Questions

1. The SI base unit for mass is:
e. kilogram

2. For which of the following situations is the conservation of mechanical energy most likely to be a valid assumption?
b. a parachutist falls from a plane

3. The slope of a line drawn tangent to a point on the curve of a position versus time graph describes what concept?
c. instantaneous velocity

4. As an object falls towards Earth:
d. the upward acceleration of Earth is negligible because of its large mass

5. Mass differs from weight in that:
b. weight is a force and mass is not

6. The main difference between kinetic energy and potential energy is that:
b. Kinetic energy involves motion, and potential energy involves position

7. A lead ball and a book are dropped from rest in a vacuum on the Moon. The acceleration of the book is:
c. zero since it floats in a vacuum

8. __________ is the unit of measurement for energy.
a. joule

9. __________ is a measure of the randomness or disorder of a system.
c. entropy

10. ________ is a thermodynamic process that takes place at constant temperature.
a. isothermal process

11. A force does work on an object if a component of the force:
b. is parallel to the displacement of the object

12. Which of the following is proportional to the kinetic energy of atoms and molecules?
b. temperature

13. Energy transferred as heat occurs between two bodies in thermal contact when they differ in which of the following properties?
d. temperature

14. What accounts for an increase in the temperature of a gas that is kept at constant volume?
b. energy has been added as heat to the gas

15. Which thermodynamic process takes place when work is done on or by the system but no energy is transferred to or from the system as heat?
c. adiabatic

Physics Concepts: Short Response Questions

1. Kinetic and Gravitational Potential Energy in Free Fall

When a pencil is on a desk, its kinetic energy is zero. Its gravitational potential energy is determined by its mass and height. When the pencil is pushed off the desk, its gravitational potential energy decreases, while its kinetic energy increases as it falls.

2. Why Solids Are Not Fluids

Solid objects are not considered fluids because they cannot flow and maintain a definite shape.

3. Thermodynamic Process Equations

a. Isothermal Process

Equation: ΔU = Q - W

In an isothermal process, the temperature remains constant, meaning ΔU = 0. Therefore, the equation simplifies to Q - W = 0, or Q = W.

Definition: A thermodynamic process that takes place at constant temperature.

b. Adiabatic Process

Equation: ΔU = Q - W

In an adiabatic process, no energy is transferred as heat (Q = 0). Therefore, the equation simplifies to ΔU = -W.

Definition: A thermodynamic process during which no energy is transferred to or from the system as heat.

c. Isovolumetric Process

Equation: W = PΔV

In an isovolumetric process, the volume remains constant (ΔV = 0), meaning no work is done (W = 0). Therefore, the first law of thermodynamics (ΔU = Q - W) simplifies to ΔU = Q.

Definition: A thermodynamic process that takes place at constant volume, so that no work is done on or by the system.

4. Free Body Diagram of a Towed Car

A free body diagram illustrates all forces acting on an object. For a car being towed, the forces typically include:

• F_Normal (or F_earth): The upward force exerted by the ground, perpendicular to the surface.
• F_Gravity (or Weight): The downward force due to Earth's gravitational pull.
• F_Applied (or Towing Force): The horizontal force pulling the car forward.
• F_Friction (or Resistance): The horizontal force opposing the motion, acting in the opposite direction of the applied force.

      ^ FNormal
      |
<-- FFriction | Car | FApplied -->
      |
      v FGravity

Note: The provided text diagram was simplified. This representation aims to clarify the forces involved.