Air resistance depends on speed because as an object moves faster through the air, it encounters more air molecules per unit of time, resulting in a greater force of air resistance. This force increases with the square of the object's speed, meaning that doubling the speed will result in four times the air resistance. Therefore, the faster an object moves, the greater the air resistance it will experience. **

The speed of a skier without friction and air resistance would be constant and would continue to increase as long as the slope remains constant. This is because there are no forces acting against the skier to slow them down. In this ideal scenario, the skier would continue to accelerate indefinitely. **

No, the air resistance does not double when the speed remains constant. Air resistance is dependent on the speed of the object moving through the air, so if the speed remains constant, the air resistance will also remain constant. However, if the speed were to double, then the air resistance would increase by a factor of four. This is because air resistance is proportional to the square of the speed of the object. **

To determine if the speed camera is valid, it is important to consider whether it has been properly calibrated and maintained according to the manufacturer's specifications and local regulations. Additionally, the location of the speed camera should comply with local laws and regulations regarding its placement. It is also important to ensure that the speed camera has been regularly tested and certified for accuracy. If all these criteria are met, then the speed camera can be considered valid. **

Yes, it is generally true that the greater the rolling resistance, the lower the maximum speed. Rolling resistance is the force that opposes the motion of a rolling object, such as a car or bicycle, and it is caused by the deformation of the object and the friction between the object and the surface it is rolling on. As rolling resistance increases, more energy is required to overcome it, which can result in a decrease in maximum speed. This is why reducing rolling resistance is a key factor in improving the efficiency and speed of vehicles. **

The air resistance of a car at a speed of 100 km/h depends on various factors such as the car's shape, size, and aerodynamics. Generally, at this speed, the air resistance can be significant and can have a noticeable impact on the car's fuel efficiency and performance. To calculate the exact air resistance, one would need to consider the car's drag coefficient, frontal area, and other aerodynamic factors. **

Yes, the water resistance of wristwatches is generally valid for saltwater as well. However, it's important to note that saltwater can be more corrosive than freshwater, so it's recommended to rinse the watch with fresh water after exposure to saltwater to prevent any potential damage. Additionally, prolonged exposure to saltwater can still compromise the water resistance of the watch over time, so it's best to follow the manufacturer's guidelines for water resistance and maintenance. **

Without seeing the actual photo, it is difficult to determine the validity of the speed camera photo. However, speed camera photos are typically considered valid evidence of a speeding violation if they clearly show the license plate of the vehicle and the speed at which it was traveling. It is important to review the photo carefully and consider any potential issues, such as visibility or accuracy, before determining its validity. **