Calculating Force of Car and Driver at Rest

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Homework Help Overview

The problem involves a car and a driver starting from rest and accelerating to a specified speed. It focuses on calculating the force acting on the rider, considering the masses of both the car and the rider.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss whether to calculate the force on the rider alone or to consider the combined mass of the car and rider. Questions arise about the interpretation of the problem statement and the relationship between the car and the driver as a system.

Discussion Status

Some participants have offered clarifications regarding the focus on the rider's force versus the total force involving both the car and the rider. Multiple interpretations of the problem are being explored, particularly concerning how to approach the calculation based on the given information.

Contextual Notes

The original poster expresses uncertainty about whether to treat the car and driver as a single system or separately for the purpose of calculating force. The specific wording of the question is also under consideration.

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Homework Statement



A car starts from rest at a stop sign and accelerates to speed 15m/s in a time of 6 seconds. The mass of the car is 300kg and the mass of the rider is 100kg. What is the force on the rider?

Homework Equations



I figured the acceleration to be 2.5m/s/s. And I know that F = ma.

The Attempt at a Solution



I'm not sure if you calculate the force on the car and the driver (400kg), or just the force on the driver (100kg).

So the equation is either F=(100)(2.5) or F=(400)(2.5). Which one? Do the car and driver act as one mass?
 
Last edited:
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It asks for "the force on the rider". Not the car.
 
I just thought that the driver was in system with the car, so their masses would add up? Is that ever the case?
 
If they ask you for the total force you need to push the car AND driver (i.e. how much force does the engine need to provide) then you would add them.
 

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