Velocity due to increasing mass

AI Thread Summary
The discussion revolves around calculating the speed of a car after its mass increases from 50kg to 70kg while maintaining an initial speed of 10m/s. Participants highlight the ambiguity in the problem, noting that it does not specify how the mass increase occurs, which affects the approach to the solution. The suggestion is made to use conservation of momentum, as no external force is acting on the car during the mass increase. There is also mention of kinetic energy equations, but the focus remains on momentum conservation for this scenario. Overall, the key point is the need for clarity on the conditions of the mass increase to determine the correct calculation method.
fondrika
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Homework Statement


if a 50kg car has a static speed of 10m/s, then what is it speed if the mass of the car increased by 20kg(so that the mass of the car now is 70kg)


Homework Equations





The Attempt at a Solution


what kind of equation should i use?
i was wondering if i can use the equation of kinetic energy?
 
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Hi fondrika! Welcome to PF :smile:

The question is a bit strange. It does not specify how the mass of the car increased, because it could be due to any reason like an inelastic collision, or that the mass was just placed on the car, was there an acceleration(impulsive force) as the mass was increased? etc.

But just considering a mass added to the car without any external force acting on the car in the direction of its motion, I would probably use conservation of momentum.
 

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