Calculating Force Required to Overcome Resistance of Road & Wind at 75.0km/hr

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SUMMARY

The discussion focuses on calculating the force required to overcome road and wind resistance for a car traveling at 75.0 km/hr. It is established that 63.0% of the engine's output power, which is 69.00 HP (equivalent to 51,474 Watts), is utilized for overcoming this resistance. The correct approach involves converting the speed from kilometers per hour to meters per second to accurately compute the force in Newtons using the formula: power = force x distance/time.

PREREQUISITES
  • Understanding of power calculations in physics
  • Knowledge of unit conversions, specifically from km/hr to m/s
  • Familiarity with the relationship between horsepower and watts
  • Basic grasp of Newton's second law of motion
NEXT STEPS
  • Learn about unit conversion techniques, specifically speed conversions
  • Study the relationship between power, force, and velocity in physics
  • Explore the implications of aerodynamic drag on vehicle performance
  • Investigate the calculations involved in determining total resistance forces on vehicles
USEFUL FOR

Automotive engineers, physics students, and anyone involved in vehicle performance analysis or aerodynamics will benefit from this discussion.

jacksondwrd
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You are testing a new car in a wind-tunnel for road and wind resistance. At a speed of 75.0 Km/hr you have found that 63.0 % of the total output power of an automobile engine is used in overcoming the resistance of the road and wind against the movement of the car. If the output power of a particular car engine is 69.00 HP, what is this resistance (ie. what is the force)? Give your answer in Newtons. (Take one HP as 746 Watts.


so i was like calcualting it like this

69HP=51474
and 60% of 51474 is 32428.62

then i did the formula of the power

power=forcexdistance/time

and got that answer but it is wrong

can anyone explain to me what i did wrong here
 
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I am guessing you did not convert your 75 km/hr in SI units m/s. If you didn't, you won't get your answer in Newtons.
 

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