Conservation of Energy, Car Driving with Drag Force

In summary, a 710kg car is driving at a constant speed of 23m/s and facing a drag force of 500 N. To determine the power required from the car's engine, we can use the equation P = F*v, where F is the force overcome and v is the speed. For the first question, on level ground, the mass of the car does not affect the power consumption. However, for the second question, going up a hill with a slope of 2.0o, we must take into account the additional force due to gravity (m*g*sin(2°)) and add it to the drag force of 500 N. The power consumption can then be determined using the
  • #1
David Mordigal
6
0

Homework Statement


A 710kg car drives at a constant speed of 23m/s . It is subject to a drag force of 500 N. What power is required from the car's engine to drive the car (a) on level ground? (b) up a hill with a slope of 2.0o? Express your answer to two significant figures.

Homework Equations


p = mv
P = ΔW/Δt (but no time information given)

The Attempt at a Solution


I am not sure where to begin. I understand that power is the change in work with respect to time, but there is no time information given in the problem, so I am a little lost.
 
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  • #2
The car is moving on level ground and up the hill at constant speed. Speed has got time in it. Why can't you use that?
 
  • #3
Since constant speed is the situation, the for and against forces are equal.
On level ground the mass of the car doesn't come into it.
Then :
Power consumption ( Watts ) = force overcome (N) * speed (m/s)
(applies to constant or instantaneous speed only)
In the uphill problem, calculate the additional force acting against the car and down the slope due to gravity ( m * g * sine (2 ° ) ) and add to the 500 Newtons of drag, then calculate the power consumption.
 
  • #4
This question is probably moot by now, given that it was first posted in Nov. 2014 and the OP never replied.
 
  • #5
OK, thanks
 

Related to Conservation of Energy, Car Driving with Drag Force

What is conservation of energy and how does it relate to car driving?

Conservation of energy is a fundamental principle in physics that states that energy cannot be created or destroyed, only transferred or converted from one form to another. In the context of car driving, this means that the total energy of the system (the car and its surroundings) must remain constant. This means that the energy used to power the car's motion must come from a source, such as fuel, and that energy will be lost due to drag force and other factors.

What is drag force and how does it affect car driving?

Drag force is a resisting force that acts on an object moving through a fluid, such as air. In the context of car driving, drag force is the force that acts against the motion of the car as it moves through the air. This force is proportional to the speed of the car and the density of the air, and it can significantly affect the efficiency and performance of the car.

How do car manufacturers design cars to reduce drag force?

Car manufacturers use various design techniques to reduce drag force and improve the aerodynamics of their cars. This can include shaping the exterior of the car to minimize air resistance, using materials that are more aerodynamic, and incorporating features such as spoilers and diffusers to control air flow and reduce drag. Advanced technologies, such as wind tunnel testing and computational fluid dynamics, are also commonly used to optimize a car's design for reduced drag force.

What is the impact of drag force on fuel efficiency and range in electric cars?

Drag force has a significant impact on the fuel efficiency and range of electric cars. As electric cars rely on a battery to power their movement, any additional resistance, such as drag force, will require more energy to overcome. This means that electric cars with more aerodynamic designs will have better fuel efficiency and longer range compared to those with less aerodynamic designs.

How can drivers reduce the effects of drag force when driving?

There are several ways that drivers can reduce the effects of drag force when driving. These include driving at a steady speed, avoiding rapid acceleration and braking, and keeping the car's exterior clean and free from any added resistance, such as mud or snow. Additionally, using cruise control on highways and reducing the use of accessories, such as air conditioning, can also help to minimize the impact of drag force on the car's performance and fuel efficiency.

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