12 energy homework questions: bowling swing, work, power, pole vault

[fphysicsclass]

Oh god. I got a 95 on the kinematics test, studied forever hoping that this stuff wouldn't come back to haunt me... and now it has. We just started the work/energy/optics unit. I want to understand this.

So from deriving several equations I got v = deltax/sqrt(deltay/.5g)

Assuming that the initial horiz. speed was 5.9 m/s, I got deltay = .45m

 

[fphysicsclass]

My answer is closest to .4 m. Do you think that's right?

 

[flyingpig]

Huh, interesting.

Try this

x = vt (x is horizontal distance)

y = -gt^2/2 + 2 (vertical distance, check that t = 0, y = 2)

There is no velocity before because it is freefalling.

Your answer is wrong, because the base of the ramp is 2m high, why would it be 0.4m...? But I am not really reading your posts so I am not much of help, but I have set up some eqtns for you

 

[fphysicsclass]

I mean 2.4 m because you must add 2 to the .4m.

 

[fphysicsclass]

See, my derived equation allows me to neglect time! :D
I found it by myself... so proud.

However, I think I neglected to add 2 m to .4 m because it asks for with respect to the floor. Look:

8. A marble rolls down a ramp that sits on table. The marble leaves the base of the ramp with a horizontal velocity. The base of the ramp is 2 meters above the floor. The marble strikes the floor at a distance of 1.8 meters from where it left the ramp. Give the height of the ramp with respect to the floor.
Choose one answer.
2.4 m
0.4 m
4.4 m
1.4 m
2.2 m

 

[Pengwuino]

Yup, so remember they want the height from the floor so the answer should be 2.4m