I suck at this.I try to do some exercises maybe i will get something but i can't really do anything...I've done some parts of the exercises but i can't do some of them.Can somebody explain me how I must do them and why it's like that?

 

1.We have an object m=1kg).It's on the ground but it's going up(vertically) with a speed of 10m/s.

The air friction doesn't matter and the gravitational potential energy is considered 0 at the ground level.

 

The question is : what's the speed of the object when potential energy is the same with the kinetic energy?

 

2.Look at this..."picture".I translate the data here:

 

http://i.imgur.com/wfZJmlQ.jpg

 

m=5kg

v0=10m/s

B=30 degrees.

BC friction=0,58

The object starts from B and stops at C.What's the maximum height it can reach?

 

 

 

 

Step 1: what are the relevant formulas in both cases?

Step 1: what are the relevant formulas in both cases?

Kinetic and potential energy?I don't think they are the same in both languages...i try do write them like this:

 

Potential energy= mass*gravitational acceleration*height

Kinetic energy= mass*speed^2/2

 

Tell me if they are the same in english and romanian:

 

Ec=mgh

Ep=mv^2/2

 

I'm not sure if these are the formulas but...

One step at a time.

 

 

1.We have an object m=1kg).It's on the ground but it's going up(vertically) with a speed of 10m/s.

The air friction doesn't matter and the gravitational potential energy is considered 0 at the ground level.

 

The question is : what's the speed of the object when potential energy is the same with the kinetic energy?

 

You say the 1kg mass is travelling vertically upward at a speed of 10m/s.

 

So is it accelerating or decelerating or is the speed constant?

 

Please tell me why (or why not) in each instance.

Edited June 14, 201411 yr by studiot

One step at a time.

 

 

You say the 1kg mass is travelling vertically upward at a speed of 10m/s.

 

So is it accelerating or decelerating or is the speed constant?

 

Please tell me why (or why not) in each instance.

It doesn't say but it was asking about the speed when it hits the ground too so its decelerating.

 

It doesn't say but it was asking about the speed when it hits the ground too so its decelerating.

 

 

 

In physics (and other sciences) every word is important and means something or it would not be there.

 

I'm sorry you have to translate from your native Romanian to English but we must try.

 

So we cannot guess the problem you must tell us all of it.

 

 

In physics (and other sciences) every word is important and means something or it would not be there.

 

I'm sorry you have to translate from your native Romanian to English but we must try.

 

So we cannot guess the problem you must tell us all of it.

Ok...here is for the second one(the one with the ss)

 

An object(m=5kg) is launched with an initial speed v0=10m/s from the point A,on a horizontal surface like in the near draw.After the distance AB=5m on the horizontal surface the object enters on the oblique surface(alpha angle is 30 degrees) and travells until point C,where it stops.On both surfaces the friction is present. on AB the friction is 0,5 and on BC is 0,58.

Well from what I can see, you gave fuzzwood the correct formulae for energy, but you are having trouble understanding acceleration.

 

For this reason you should complete (1) first since it is easier, and properly answer my three questions about it.

 

As regards question (2)

 

Do you think this is an energy question?

 

Do you know the formulae (equations of motion) for a body with zero acceleration and constant acceleration?