Explaining Velocity Increase on Ramp: Gravity & Slope

[zmike]

Homework Statement

Explain in detail (include gravity, etc...) why a ball would have greater velocity when rolling down a ramp (same thickness and composition) with greater slope than one without.

Homework Equations

acceleration = v/t
gravity = -9.81 m/s

The Attempt at a Solution

Gravity is always constant so it really shouldn't change no matter the slope. Perhaps there is another force at work, but I have no idea what it might be (only gr.11 physics).

thanks

 

[cristo]

Newton's second law states that the force applied to a body is proportional to the acceleration of the body. What is the force in this situation that produces an acceleration down the slope? Does this increase or decrease when the gradient of the slope is greater? Do you need to include effects of friction? (i.e. have you studied it?)

 

[zmike]

I am assuming that the ball is simply placed on the ramp so the only force should be gravity but I think there should be another force involved. I haven't studied friction yet but my teacher expects that we have a very basics understanding of it.

 

[arildno]

If it rolls and accelerates, you should indeed include in your analysis the role of the frictional force.

 

[robb_]

Well, gravity is not the only force. If it rolls there must be friction. Also, does the ramp exert a force?

 

[zmike]

I haven't studied frictional force yet. Is there a very simple explanation I can give (in less than 5 sentences) of why it has a higher velocity.

The ball should experience uniform acceleration since I recall from the "ramp lab" (used kinematic carts with motion detectors) that even though the slopes were increased the acceleration was still a straight horizontal line for all of them. This means that the slope of the ramp only effects the slope of the velocity graph. This would mean that there should a separate force acting on objects on an inclined plane besides gravity that changes the slope of the velocity graph. Am I right?

 

[zmike]

I am really confused, I've read over my textbook five times and I can't find anything useful. I really don't understand why changing the slope of a ramp will change an object's velocity or acceleration?

I really need help, I have to e-mail my teacher my lab before 12 am.

thanks