in einsteins mass energy equation what is represented by c

HESI A2

HESI A2 Physics Quizlet

1. In Einstein’s mass-energy equation, what is represented by c?

A. Distance in centimeters
B. The speed of light
C. Degrees Celsius
D. Centrifugal force

Correct answer: B

Rationale: In Einstein's mass-energy equation, E=mc^2, the symbol 'c' represents the speed of light in a vacuum, which is approximately equal to 3.00 x 10^8 meters per second. This equation demonstrates the equivalence of energy (E) and mass (m) and is a fundamental concept in the theory of relativity. Choice A is incorrect as 'c' does not represent distance in centimeters. Choice C is incorrect as 'c' does not represent degrees Celsius. Choice D is incorrect as 'c' does not represent centrifugal force.

2. Two objects attract each other with a gravitational force of 12 units. If you double the mass of both objects, what is the new force of attraction between them?

A. 3 units
B. 6 units
C. 24 units
D. 48 units

Correct answer: C

Rationale: The gravitational force between two objects is directly proportional to the product of their masses. When you double the masses of both objects, the force of attraction between them increases by a factor of 2 x 2 = 4. Therefore, the new force of attraction between the two objects will be 12 units x 4 = 24 units. Choices A, B, and D are incorrect because doubling the mass results in a quadruple increase in force, not a linear one.

3. A Carnot cycle is a theoretical ideal heat engine operating between two heat reservoirs at different temperatures. Which of the following statements is NOT true about a Carnot cycle?

A. The efficiency of a Carnot cycle is solely dependent on the absolute temperatures of the hot and cold reservoirs.
B. It is a reversible cycle, meaning the process can be run in both directions with the same efficiency.
C. It operates isothermally at the hot and cold reservoir temperatures.
D. It is the most efficient heat engine operating between the same two reservoir temperatures.

Correct answer: C

Rationale: The statement that is NOT true is C. Although part of the Carnot cycle operates isothermally, not the entire cycle operates isothermally. The Carnot cycle consists of both isothermal and adiabatic processes. Choice A is incorrect because the efficiency of a Carnot cycle is indeed solely dependent on the absolute temperatures of the hot and cold reservoirs. Choice B is correct as a Carnot cycle is reversible, allowing the process to be run in both directions with the same efficiency. Choice D is also true as the Carnot cycle is the most efficient heat engine operating between the same two reservoir temperatures. Therefore, the correct answer is C.

4. Why doesn’t a raindrop accelerate as it approaches the ground?

A. Gravity pulls it down at a constant rate.
B. Air resistance counteracts the gravitational force.
C. Its mass decreases, decreasing its speed.
D. Objects in motion decelerate over distance.

Correct answer: B

Rationale: The correct answer is B. As a raindrop falls, it experiences air resistance which counteracts the gravitational force pulling it down. This balancing of forces prevents the raindrop from accelerating further as it approaches the ground. Choice A is incorrect because while gravity is pulling the raindrop down, air resistance opposes this force. Choice C is incorrect as the mass of the raindrop remains constant during its fall. Choice D is incorrect because objects in motion may decelerate due to various factors, but in this case, the focus is on why the raindrop doesn't accelerate.

5. Certain non-Newtonian fluids exhibit shear thickening behavior. In this case, the fluid's viscosity:

A. Remains constant with increasing shear rate
B. Decreases with increasing shear rate (shear thinning)
C. Increases with increasing shear rate
D. Depends solely on the applied pressure

Correct answer: C

Rationale: When a non-Newtonian fluid exhibits shear thickening behavior, its viscosity increases with increasing shear rate. This means that as more force is applied to the fluid, its resistance to flow also increases, resulting in a higher viscosity. This phenomenon is opposite to shear thinning, where viscosity decreases with increasing shear rate. Therefore, in the case of shear thickening behavior, the correct answer is that the fluid's viscosity increases with increasing shear rate. Choices A, B, and D are incorrect because shear thickening behavior specifically involves an increase in viscosity with increasing shear rate, not remaining constant, decreasing, or depending on applied pressure.