Nokea
What is the net force acting on the car?
- A. 450 N
- B. 700 N
- C. 1,500 N
- D. 6,300 N
Correct Answer: C
Rationale: To determine the net force acting on an object, we need to consider the sum of the forces acting in the same direction and subtract the forces acting in the opposite direction. In this scenario, there is a force of 4,200 N to the right and a force of 2,700 N to the left. By subtracting the leftward force from the rightward force (4,200 N - 2,700 N), we find that the net force acting on the car is 1,500 N to the right. Therefore, choice C, 1,500 N, is the correct answer. Choice A, 450 N, is too small as it does not account for the total forces involved. Choice B, 700 N, is also incorrect as it is not the result of the correct mathematical operation on the given forces. Choice D, 6,300 N, is too large and does not align with the calculation based on the forces provided.
You may also like to solve these questions
The specific heat capacity of tin is 217 J/(g°C). Which of these materials would require about twice as much heat as tin to increase the temperature of a sample by 1°C?
- A. Copper [0.3844 J/(g°C)]
- B. Iron [0.449 J/(g°C)]
- C. Gold [0.1291 J/(g°C)]
- D. Aluminum [0.904 J/(g°C)]
Correct Answer: D
Rationale: The correct answer is D: Aluminum. The specific heat capacity of aluminum is 0.904 J/(g°C), which is approximately 4 times that of tin. For a material to require about twice as much heat as tin to increase the temperature by 1°C, it should have a specific heat capacity roughly double that of tin. Therefore, aluminum fits this criterion better than the other options. Gold has a much lower specific heat capacity than tin, so it would require less, not more, heat to increase the temperature by 1°C. Copper and Iron also have specific heat capacities lower than tin, making them incorrect choices for requiring twice as much heat as tin.
When a gas is compressed isothermally, we can say that:
- A. The gas performs work on the surroundings, and its internal energy increases.
- B. The gas performs work on the surroundings, and its internal energy decreases.
- C. The surroundings perform work on the gas, and its internal energy increases.
- D. The surroundings perform work on the gas, and its internal energy decreases.
Correct Answer: D
Rationale: When a gas is compressed isothermally, the surroundings perform work on the gas. In this process, since the temperature remains constant (isothermal), the internal energy of the gas does not change. Therefore, the correct answer is that the surroundings perform work on the gas, and its internal energy decreases. Choices A, B, and C are incorrect because they incorrectly describe the direction of work and the change in internal energy during an isothermal compression.
Fluids can be categorized based on their shear stress-strain rate relationship. An ideal fluid exhibits:
- A. Zero shear stress at any strain rate
- B. Linear relationship between shear stress and strain rate (Newtonian)
- C. Non-linear relationship between shear stress and strain rate (Non-Newtonian)
- D. High dependence of viscosity on temperature
Correct Answer: A
Rationale: An ideal fluid, often referred to as an inviscid fluid, is a theoretical concept used in fluid mechanics to simplify calculations. It is characterized by having zero shear stress at any strain rate. In reality, such fluids do not exist, but they serve as a useful starting point for understanding fluid behavior in idealized situations. Choice B is incorrect because a linear relationship between shear stress and strain rate defines a Newtonian fluid, not an ideal fluid. Choice C is incorrect because a non-linear relationship between shear stress and strain rate characterizes Non-Newtonian fluids, not ideal fluids. Choice D is incorrect because the high dependence of viscosity on temperature is a characteristic seen in real fluids and does not define an ideal fluid.
What is the kinetic energy of a 500-kg wagon moving at 10 m/s?
- A. 50 J
- B. 250 J
- C. 2.5 10^4 J
- D. 5.0 10^5 J
Correct Answer: C
Rationale: The formula for calculating kinetic energy is KE = 0.5 mass velocity². Given the mass of the wagon is 500 kg and the velocity is 10 m/s, we can substitute these values into the formula: KE = 0.5 500 kg (10 m/s)² = 0.5 500 kg 100 m²/s² = 25,000 J or 2.5 10â´ J. Therefore, the kinetic energy of the 500-kg wagon moving at 10 m/s is 2.5 10â´ J. Choice A (50 J) is incorrect because it is too low; Choice B (250 J) is incorrect as it does not match the correct calculation; Choice D (5.0 10^5 J) is incorrect as it is too high. The correct answer is C (2.5 10^4 J).
What force was applied to the object that was moved if 100 Nâ‹…m of work is done over 20 m?
- A. 5 N
- B. 80 N
- C. 120 N
- D. 2,000 N
Correct Answer: A
Rationale: Work is calculated using the formula Work = Force x Distance. Given that 100 Nâ‹…m of work is done over 20 m, we can rearrange the formula to solve for Force. Force = Work / Distance. Plugging in the values, we get Force = 100 Nâ‹…m / 20 m = 5 N. Therefore, the force applied to the object that was moved is 5 N.
Choice B (80 N) is incorrect because it doesn't match the calculated force of 5 N. Choice C (120 N) is incorrect as it is higher than the calculated force. Choice D (2,000 N) is incorrect as it is significantly higher than the correct force of 5 N.