Forces and work on an incline help!

1. Feb 27, 2009

northern expo

we are conducting a lab where measurement of force on an incline is necessary. the mass which is pulled is a small concrete block (15.8 kg) on a wooden ramp. as the ramp is increased the force changes (increasing) which is expected. last we need to look at the coefficient of friction at different angles of measure. if we are pulling the block up the ramp at a constant we are finding a force of oppositon due to friction and the force normal. ok, as we are calculating we are finding that the value of this coefficient is increasing and at about 47 degrees of the horizontal plane this value is greater than 1!!!!!! at the lower angles it is a reasonable value. what are we forgetting? yes we are considering that the force normal is a cosine function of the weight and the force parrallel is the froce we are applying up the ramp. doesn't seem to be correct. what are we missing?

2. Feb 27, 2009

LowlyPion

F = m*g*sinθ + μ*m*g*cosθ

I'm just saying, since you didn't mention the component of weight down the incline at sinθ.

3. Feb 27, 2009

northern expo

is this F value you are indicating the net F ? We have a measured value for the force up the incline, how is this value

F = m*g*sinθ + μ*m*g*cosθ

included into my equation to find the coefficient value?