Nursing Elites

1. An electromagnet is holding a 1,500-kg car at a height of 25 m above the ground. The magnet then experiences a power outage, and the car falls to the ground. Which of the following is false?

• A. The car had a potential energy of 367.5 kJ.
• B. 367.5 kJ of potential energy is converted to kinetic energy.
• C. The car retains potential energy of 367.5 kJ when it hits the ground.
• D. The car’s potential energy converts to kinetic energy and then to sound energy.

Correct answer: C

Rationale: When the car falls to the ground, its potential energy is converted to kinetic energy as it accelerates downwards. Upon impact with the ground, the car's kinetic energy is dissipated in various forms, such as sound energy, heat, and deformation energy. Therefore, the car does not retain its initial potential energy of 367.5 kJ when it hits the ground. Choice A is true because the potential energy of the car can be calculated as mgh = 1500 kg * 9.8 m/s^2 * 25 m = 367,500 J = 367.5 kJ. Choice B is true because as the car falls, its potential energy is converted to kinetic energy. Choice D is true as the kinetic energy is eventually dissipated into other forms upon impact.

2. Two objects attract each other with a gravitational force of 12 units. If the distance between them is halved, what is the new force of attraction between the two objects?

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

Correct answer: C

Rationale: The gravitational force between two objects is inversely proportional to the square of the distance between them. When the distance is halved, the new force of attraction will be 12 units x (1/(0.5)^2) = 12 units x 4 = 24 units. Therefore, the correct answer is C. Choice A and B are incorrect as they do not consider the inverse square law of gravitational force. Choice D is incorrect as reducing the distance between the objects does not lead to a squared increase in force.

3. A 10-kg object moving at 5 m/s has an impulse acted on it causing the velocity to change to 15 m/s. What was the impulse that was applied to the object?

• A. 10 kg⋅m/s
• B. 15 kg⋅m/s
• C. 20 kg⋅m/s
• D. 100 kg⋅m/s

Correct answer: D

Rationale: Impulse is the change in momentum of an object. The initial momentum is calculated as 10 kg × 5 m/s = 50 kg⋅m/s, and the final momentum is 10 kg × 15 m/s = 150 kg⋅m/s. The change in momentum (impulse) is 150 kg⋅m/s - 50 kg⋅m/s = 100 kg⋅m/s. Therefore, the impulse applied to the object is 100 kg⋅m/s. Choices A, B, and C are incorrect because they do not reflect the correct calculation of the impulse based on the change in momentum of the object.

4. An object with a charge of 3 μC is placed 30 cm from another object with a charge of 2 μC. What is the magnitude of the resulting force between the objects?

• A. 0.6 N
• B. 0.18 N
• C. 180 N
• D. 9 × 10−12 N

Correct answer: B

Rationale: To find the magnitude of the resulting force between two charges, we use Coulomb's Law: F = k × (|q1 × q2|) / r² Where: F is the force k is Coulomb’s constant (8.99 × 10⁹ N·m²/C²) q1 and q2 are the charges r is the distance between the charges Plugging in the values: F = (8.99 × 10⁹) × (3 × 10⁻⁶) × (2 × 10⁻⁶) / (0.3)² = 0.18 N. Therefore, the magnitude of the resulting force is 0.18 N.

5. A car, starting from rest, accelerates at 10 m/s² for 5 seconds. What is the velocity of the car after 5 seconds?

• A. 2 m/s
• B. 5 m/s
• C. 50 m/s
• D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: The velocity of an object can be calculated using the formula: final velocity = initial velocity + (acceleration × time). In this case, the car starts from rest, so the initial velocity is 0 m/s. Given that the acceleration is 10 m/s² and the time is 5 seconds, we can plug these values into the formula to find the final velocity: final velocity = 0 m/s + (10 m/s² × 5 s) = 0 m/s + 50 m/s = 50 m/s. Therefore, the velocity of the car after 5 seconds is 50 m/s. Choice A (2 m/s) and Choice B (5 m/s) are incorrect because they do not consider the acceleration the car undergoes over the 5 seconds, resulting in a final velocity greater than both. Choice D (The answer cannot be determined from the information given) is incorrect as the final velocity can be determined using the provided data and the kinematic equation.

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