# Physics Problem

1. Jan 30, 2006

### imdiskid06

A small block of mass .5kg is released form rest at the top of a curved-shaped frictionless wedge of mass 3 kg , which sits on a frictionless horizontal surfces. When the block leaves the wedge, its velocity is 4 m/s to the right. Find the velocity of the wedge after the block reaches the horizontal surface. What is the height of the wedge?

2. Jan 31, 2006

### Meir Achuz

1. Use conservation of momentum:MV+mv=0.
2. Use conservation of energy:MV^2+mv^2=2mgH.

3. Feb 2, 2006

### kingkong

hello everyone!

i am doing an investigation on the inverse square law of radiation, and i have plotted a graph of 1/rsquared angainst intensity of light. I have one point which for when the detector is closest to the point source (bulb) that is far from the line of best fit to the right side of the graph. how do i explain this?????

4. Feb 2, 2006

### Meir Achuz

You may be so close to the bulb that it no longer looks like a point source.
That would be if distance were not large compared with the radius of the bulb.

5. Feb 2, 2006

### kingkong

well the distance between the bulb and the detector was 0.05m. the radius of the bulbs was approx 9mm. help me

6. Feb 2, 2006

### kingkong

does any-one know of any applications of the inverse law. could you appoint me a website link

7. Feb 3, 2006

### Meir Achuz

When you are that close, the inverse square law does not apply.
A website won't change that.

8. Feb 4, 2006

### kingkong

could you give some mathematical proof.

9. Feb 4, 2006

### kingkong

hello,

i need to know the mathematics involving the inverse law is used in predicting floods and their impact.

10. Feb 4, 2006

### kingkong

Could you give me some examples where the inverse law is used.

11. Dec 15, 2009

### janlinh

Why is it 2mgH?