Velocity Related Questions TBR1

[glam407]

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. How does the mass of the vehicle affect its braking distance?

A. Mass has no effect on the braking distance (this is the correct answer)

But I don't understand why mass has no effect on braking distance?

 

[okokok]

I'm weak in physics, so someone else should say if this is correct or not, but I think it's because this question is asking about the force of friction. The mass of the car doesn't figure into the total net force acting on the car because it's canceled out by the normal force.

Braking against friction has to do with forces in the x direction, while weight is a y direction force and canceled out anyway by normal force.

I think.

I hate physics.

 

[Postictal Raiden]

. How does the mass of the vehicle affect its braking distance?

A. Mass has no effect on the braking distance (this is the correct answer)

But I don't understand why mass has no effect on braking distance?

It may seem counter intuitive to realize that the mass has no effect on the breaking distance since we know that mass effects the normal force, and thus the force of friction. However, you need to remember that the opposing force, F of the vehicle, also has mass as a component, so mass ends up canceling out on both sides of the equation.

KE of the moving car = Energy needed to bring the car to stop
1/2 mv^2 = Force of friction x d
1/2 mv^2 = umg x d (m cancels out)
(v^2)/(2ug) = d