the coefficient of friction between a car and dry pavement is approximately 0.7, but the coefficient on wet pavement is 0.4 or less. what does this indicate about driving on wet pavement?
a a car’s normal force is less on wet pavement.
b a car’s normal force is greater on wet pavement.
c a car requires less applied force to move on wet pavement.
d a car requires more applied force to move on wet pavement.

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# Brief Explanations:
The coefficient of friction ($\mu$) relates to friction force ($F_f = \mu F_N$, where $F_N$ is normal force). For a car, normal force equals weight (so same on wet/dry, eliminating A/B). Lower $\mu$ on wet means friction force ($F_f$) is less. To drive, friction provides traction (applied force from tires, related to friction). Lower $\mu$ on wet means less friction, so a car needs less applied force? Wait, no—wait, when driving, the friction is the force that propels? No, actually, for braking or accelerating, friction is the force. Wait, the question is "what does this indicate about driving on wet pavement?" Let's re-express: $\mu_{dry} \approx 0.7$, $\mu_{wet} \leq 0.4$. Friction force $F_f = \mu F_N$. Since $F_N$ (normal force, from weight $mg$) is same for dry/wet (same car, same weight), lower $\mu$ means lower $F_f$. Now, the options:

- A: Normal force less on wet? No, $F_N = mg$, same.
- B: Normal force greater? No.
- C: A car requires less applied force to move on wet? Wait, no—wait, when driving, the force needed to move (or accelerate) depends on friction. If friction is lower (wet), the maximum friction (traction) is lower, so the car can apply less force (because friction can't provide more than $\mu F_N$). Wait, or maybe: the friction force is the force that allows the car to move (static friction for rolling). Lower $\mu$ means less friction, so the car needs less applied force? Wait, no—if you want to accelerate, the force from the tires (applied force) is limited by friction. So with lower friction (wet), the maximum applied force (traction) is lower, meaning the car must apply less force (otherwise it slips). So option C: "A car requires less applied force to move on wet pavement" makes sense? Wait, no, maybe I got it wrong. Wait, the coefficient of friction being lower means that the friction force is lower. So when driving, the force you can apply (without slipping) is limited by friction. So on wet, since friction is lower, you can't apply as much force (otherwise the tires slip). So the car requires less applied force (because the available friction is less). So option C is correct? Wait, let's check the options again:

Option C: "A car requires less applied force to move on wet pavement."

Option D: "A car requires more applied force to move on wet pavement."

Since $\mu$ is lower on wet, $F_f = \mu F_N$ is lower. So the maximum force the car can apply (before slipping) is lower. Therefore, to move (accelerate) without slipping, the car must apply less force. So option C is correct? Wait, but maybe I mixed up. Wait, the question is about what the lower coefficient indicates. Let's re-express:

Coefficient of friction is lower on wet. So friction force is lower. Therefore, when driving, the force that the car can use (from friction) is lower. So the car needs to apply less force (because if it applies more, it will slip). So option C is correct. Wait, but let's confirm the normal force: normal force is equal to the weight of the car (since it's on a horizontal surface), so $F_N = mg$, same for dry and wet. So A and B are wrong. Then, between C and D: lower friction means less force available, so the car must apply less force (otherwise it slips). So C is correct.

Wait, but maybe the question is about braking? No, the question is about driving (moving). So the key is that lower friction means less traction, so the car can't apply as much force (so requires less applied force to avoid slipping). Therefore, option C is correct.

Wait, but maybe I made a mistake. Let's think again: The coefficient of friction is the ratio of friction force to normal force. Lower $\mu$ means less friction for the same normal force. So when driving, the force you can apply (the force from the tires pushing the road, which is equal and opposite to the friction force) is limited by friction. So on wet, since friction is lower, the maximum force you can apply (without slipping) is lower. Therefore, the car requires less applied force (because if you apply more, it slips). So option C is correct.

# Answer:
C. A car requires less applied force to move on wet pavement.

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