# Homework Help: Motion on inclined plane

1. Dec 12, 2008

### physiker99

Assume there is no friction in the system. Can anyone write formulas for acceleration of both the small object and the triangular object? (Gravity is downwards, no other force such as air drag etc.)

[URL=http://imageshack.us][PLAIN]http://img83.imageshack.us/img83/6036/asdasdcf6.png[/URL][/PLAIN]

2. Dec 12, 2008

### Danger86514

I would draw the free body diagrams for both objects first ... then remember "In the absence of friction and other forces (tension, applied, etc.), the acceleration of an object on an incline is the value of the parallel component (m*g*sine of angle) divided by the mass (m). This yields the equation : a = g sin (alpha)

Reference: http://www.glenbrook.k12.il.us/gbssci/Phys/Class/vectors/u3l3e.html [Broken]

for the Triangular object. The applied force would be the Normal force from the smaller block ... the acceleration should come from the force paralell to the ground ..

Last edited by a moderator: May 3, 2017
3. Dec 12, 2008

### Staff: Mentor

While your advice to draw free body diagrams is excellent, a = g sin (alpha) only holds if the incline is fixed. But this one can move.

4. Dec 13, 2008

### Danger86514

thanks, but I was only giving some points in the right direction. i was hoping that would have physiker99 think some .. in the future I will keep this in mind and just do the work for them ... i am new to the thread and was under the impression that the questions are not just answered with a blunt response.

attached is a pdf ....

#### Attached Files:

• ###### incline.pdf
File size:
49.7 KB
Views:
60
5. Dec 13, 2008

### Staff: Mentor

No one is suggesting that you do the work for them, but don't you think that any comment you make should at least be correct?