Conservation of Energy, Car Driving with Drag Force

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SUMMARY

The discussion focuses on calculating the power required for a 710 kg car traveling at a constant speed of 23 m/s, facing a drag force of 500 N. For level ground, the power consumption is determined using the formula: Power (Watts) = Force (N) * Speed (m/s), resulting in a power requirement of 11,500 Watts. When driving uphill at a 2.0° slope, the additional gravitational force must be calculated using the formula: m * g * sin(2°), which adds to the drag force, necessitating a recalculation of power consumption.

PREREQUISITES
  • Understanding of basic physics concepts such as force, power, and work
  • Familiarity with the equations of motion and constant speed scenarios
  • Knowledge of trigonometric functions, specifically sine for slope calculations
  • Ability to perform unit conversions and calculations involving Newtons and Watts
NEXT STEPS
  • Calculate power requirements for different drag forces and speeds
  • Explore the impact of varying slopes on power consumption in vehicles
  • Learn about the relationship between mass, speed, and energy in physics
  • Investigate real-world applications of drag force in automotive engineering
USEFUL FOR

Students studying physics, automotive engineers, and anyone interested in the principles of energy conservation and vehicle dynamics.

David Mordigal
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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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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?
 
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.
 
This question is probably moot by now, given that it was first posted in Nov. 2014 and the OP never replied.
 
OK, thanks
 

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