Based on the scenario below, choose the best answer.A car is driving up a slope at a constant velocity. This means:

Question

BlackTom AI · Accepted Answer

Newton's first law (equilibrium) implies that an object moving at constant velocity has zero net force acting on it.

1. Relevant knowledge points and concepts
- Newton's first and second laws: constant velocity ⇒ acceleration a = 0 ⇒ ΣF = 0.
- Forces on an inclined plane: weight mg (acts vertically), normal force N (perpendicular to surface), frictional force f (parallel to surface, opposing motion), and the engine/drive force Fdrive (if the car is powered).
- Components of weight: parallel to slope = mg sinθ (down the slope); perpendicular to slope = mg cosθ.

2. Step-by-step reasoning
- Because the car moves up the slope at constant speed, acceleration along and perpendicular to the surface is zero.
- Take axes: x along the slope (positive up the slope), y perpendicular (out of the surface).
- Along x: ΣFx = Fdrive - f - mg sinθ = 0. This says the driving force balances friction and the downhill component of weight.
- Perpendicular: ΣFy = N - mg cosθ = 0 ⇒ N = mg cosθ.

3. Intermediate steps (equations)
- ΣFx = 0 ⇒ Fdrive = f + mg sinθ.
- ΣFy = 0 ⇒ N = mg cosθ.

4. Why the correct answer is correct
- The statement "the net force is zero" (option b) follows directly from ΣF = ma with a = 0. None of the other options state the general condition required by constant velocity.

5. Why other options are incorrect
- a. "Frictional force equals the normal force." Friction is not generally equal to the normal force; static/kinetic friction magnitude is related by f ≤ μN or f = μkN only for limiting/kinetic cases, not universally equal.
- c. "The weight force equals the frictional force." Weight (mg) is generally much larger and acts vertically; its components appear in balance equations, but mg ≠ f in general.
- d. "The weight force equals the normal force." On an incline N = mg cosθ, which is less than mg for θ ≠ 0; equality holds only for a horizontal surface.

6. Conclusion
Therefore the best answer is b. The net force is zero. This matches the provided correct answer.

Based on the scenario below, choose the best answer.A car is driving up a slope at a constant velocity. This means:单项选择题

类似问题

How are you to measure the angle of the slope for this experiment?

A 15.5 kg mass, slides down a rough inclined plane at an angle of 33.1 to the horizontal, experiencing a frictional force of 6.8 N.Determine the net force acting on the mass.

A 19 kg mass, slides down a rough inclined plane at an angle of 32.5 to the horizontal, experiencing a frictional force of 6.7 N.Determine the acceleration of the mass.

A 80 kg man skis down a frictionless ski slope at an angle of 12.5o to the horizontal. What is his acceleration? Give your answer to one decimal place.

A car of mass 1357.7 kg rolls down a sloping road when the handbrake fails. The road slopes at an angle of 5.3 degrees to the horizontal, and the frictional forces on the car add up to 168.1 newton.What is the net force acting on the car?

A 20 kg girlslides down a frictionless slide at a playground. The surface of the slide is 8.0o to the horizontal. What is her acceleration? Give your answer to one decimal place.

A 114 kg boulder slides down a sloping hillside during a landslide. The hillside slopes at an angle of 9.7 degrees to the horizontal, and the frictional forces on the boulder add up to 111.3 N.What is the boulder's acceleration down the slope?

An object rests on an inclined slope. Which of the following statements is true?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单