# Dynamics Question: Calculate Resistive Force on Car

• K.QMUL
In summary, resistive force, also known as drag force, is a force that acts opposite to the motion of an object and is caused by the interaction with the surrounding air or fluid. It can be calculated using a formula that takes into account factors such as speed, size, and properties of the air. This force can have a significant impact on a car's performance, but it can be reduced through design and material choices. However, it cannot be completely eliminated.
K.QMUL

## Homework Statement

Along a certain section of road a car (mass 1600kg) will coast in neutral at a constant speed of 72 km/h if there is no wind. Examination of a topological map shows that for this section of road the elevation decreases by 200m for each 6000m of road. What is the total resistive force (friction plus air resistance) that acts on the car when it is traveling at 72 km/h?

P=FV, f=ma

## The Attempt at a Solution

Please see the image attached

-Thanks for any help

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## 1. What is resistive force?

Resistive force, also known as drag force, is a type of force that acts in the opposite direction to the motion of an object. It is caused by the interaction of the object with the surrounding fluid or air.

## 2. How do you calculate the resistive force on a car?

The resistive force on a car can be calculated using the formula: Resistive Force = 0.5 * Drag Coefficient * Density of Air * Velocity^2 * Surface Area of the Car. This formula takes into account the speed and size of the car, as well as the properties of the surrounding air.

## 3. What factors affect the resistive force on a car?

The resistive force on a car is affected by several factors, including the speed of the car, the size and shape of the car, and the properties of the surrounding air such as density and viscosity.

## 4. How does resistive force impact a car's performance?

Resistive force can have a significant impact on a car's performance. It can decrease the car's acceleration, reduce its top speed, and increase the amount of fuel it consumes. This is why car manufacturers often try to design cars with low drag coefficients to minimize resistive force.

## 5. Can resistive force be reduced?

Yes, resistive force can be reduced through various methods such as streamlining the car's design, reducing its surface area, and using materials with low drag coefficients. However, completely eliminating resistive force is not possible as it is a natural force that occurs during motion.

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