a 50 kg box of iron fishing weights is balanced at the edge of a table peter gives it a push and it falls 2 meters to the floor which of the following

HESI A2

HESI A2 Physics

1. A 50-kg box of iron fishing weights is balanced at the edge of a table. Peter gives it a push, and it falls 2 meters to the floor. Which of the following statements is true?

A. Once the box hits the floor, it loses both its kinetic and potential energy.
B. The box had kinetic energy only when it was balanced at the edge of the table.
C. The box had both kinetic and potential energy after it fell.
D. Once the box hits the floor, it loses all its kinetic energy.

Correct answer: C

Rationale: When the box is balanced at the edge of the table, it has potential energy due to its position above the ground. As Peter gives it a push, and it falls 2 meters to the floor, the box then has both kinetic energy (due to its motion) and potential energy (due to gravity). Therefore, the correct statement is that the box had both kinetic and potential energy after it fell. Option A is incorrect because the box retains its energy forms even after hitting the floor. Option B is incorrect as the box has kinetic energy both before and after falling. Option D is incorrect as the box still possesses kinetic energy even after hitting the floor.

2. An object moves 100 m in 10 s. What is the velocity of the object over this time?

A. 10 m/s
B. 90 m/s
C. 110 m/s
D. 1,000 m/s

Correct answer: A

Rationale: Velocity is calculated as the displacement divided by the time taken to cover that displacement. In this case, the object moves 100 meters in 10 seconds. Therefore, the velocity is 100 m / 10 s = 10 m/s. Choice B, 90 m/s, is incorrect as it doesn't match the calculated velocity. Choice C, 110 m/s, is incorrect as it is higher than the calculated velocity. Choice D, 1,000 m/s, is incorrect as it is significantly higher than the calculated velocity.

3. The strength of a magnetic field is measured in units of:

A. Amperes
B. Tesla
C. Volts
D. Coulombs

Correct answer: B

Rationale: The Tesla (T) is the unit of measurement for the strength of a magnetic field. One Tesla is defined as one weber per square meter. Amperes (choice A) measure electric current, Volts (choice C) measure electric potential, and Coulombs (choice D) measure electric charge, making them incorrect choices for measuring the strength of a magnetic field.

4. Why does potential energy increase as particles approach each other?

A. Attractive forces increase.
B. Attractive forces decrease.
C. Repulsive forces increase.
D. Repulsive forces decrease.

Correct answer: C

Rationale: The correct answer is C: Repulsive forces increase. As particles approach each other, the distance between them decreases, causing the repulsive forces between the particles to increase. This increase in repulsive forces leads to an increase in potential energy as the particles resist being pushed closer together. Choices A and B are incorrect because attractive forces do not increase or decrease in this scenario. Choice D is incorrect because repulsive forces actually increase as particles get closer, leading to a rise in potential energy.

5. According to the zeroth law of thermodynamics, two systems are in thermal equilibrium if:

A. They have the same pressure.
B. They have the same volume.
C. They have the same temperature.
D. They are made of the same material.

Correct answer: C

Rationale: The correct answer is C: "They have the same temperature." The zeroth law of thermodynamics states that if two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other. This implies that they have the same temperature. Choice A is incorrect because pressure is not the determining factor for thermal equilibrium. Choice B is incorrect because volume alone does not dictate thermal equilibrium. Choice D is incorrect as the materials the systems are made of do not determine thermal equilibrium according to the zeroth law of thermodynamics.