## 7 thoughts on “3.6”

1. ledrone says:

This problem is the same as 3.6 in the 11th edition

2. josephl1230 says:

For task D, wouldn't $k_1x$ be in the positive $x$ direction?

1. tutorpaul says:

I don't think it would. Could you explain your reasoning?

3. Luis Rodriguez says:

Can you explain in further detail why we don't consider the GPE? I worked it out but was confused on why that is.

1. tutorpaul says:

Sorry for only just now approving your comments... I don't check my email very often these days. As noted by the rsraggies, the equilibrium video linked above explains that the initial stretch in the spring (which accounts for the equilibrium position being different from the unstretched position) offsets the weight of the object, thus gravitation potential has been offset by an equal amount of mechanical potential energy thus both can safely be omitted from the calculations.

4. rsraggies says:

i still do not understand why we don't consider the gravitational potential energy? You said we are measuring the system from the equilibrium position so we don't consider GPE, but what does that mean exactly? isn't this mass moving up a distance x on the incline? so wouldn't that mean the GPE = mg*xsin(alpha)?

1. rsraggies says:

I just watched your equilibrium video and it all makes sense now thanks