How Efficient Is a Tire Jack Lifting a Car with a 50N Force?

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Homework Help Overview

The discussion revolves around the efficiency of a tire jack lifting a car, specifically analyzing the relationship between the force applied and the work done. The problem involves concepts from mechanics, including forces, work, and efficiency calculations.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the formula for efficiency and how to calculate work input and output. There are questions about determining the force exerted by the jack and the relationship between the distances moved by the jack and the car.

Discussion Status

Some participants are clarifying the definitions and relationships between the variables involved in the efficiency calculation. There is an ongoing exploration of how to derive the necessary values for work output and input, with some guidance provided on the formulas to use.

Contextual Notes

Participants note the mass of the car and the force required to lift it, but there is uncertainty regarding the force exerted by the jack and how to calculate the work output without that information. The discussion is framed within the constraints of a homework assignment.

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The end of the lever of a tire jack travels 7 m for every centimeter that it lifts the car. If the car has a mass of 1000 kg and a force of 50 N is needed to lift the car, what is the efficiency of the jack


Efficiency = useful work output/total work input
w = F x d, where w is work, F is force, and d is distance. (If given mass instead of force, force is found by multiplying mass (in kg) by 9.8 m/sec2 (acceleration of gravity on earth)



the useful work input would be .05 correct? because you would take the 50 N the force times the distance .001 m but i don't know how to find the work output as it doesn't tell a force.. am i missing something?
 
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Efficiency = work out / work in
work = force * distance

So Efficiency = (weight_car * distance car) / (force_jack * distance jack)
 
but i don't know what the force on the jack is...
 
It says 50N
 

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