This time I'm uncertain as to how to start:(adsbygoogle = window.adsbygoogle || []).push({});

Body A in Fig. 6-34 weighs 98 N, and body B weighs 70 N. The coefficients of friction between A and the incline are ms = 0.50 and mk = 0.27. Angle is 48°. Let the positive direction of an x axis be down the slope. What is the acceleration of A if A is initially (a) at rest, (b) moving up the incline, and (c) moving down the incline?

I'm sorry I can't produce the figure but it seems to be your standard two blocks tugging on each other on an inclined plane situation.

I figured the answer to a would be 0, since an object at rest stays at rest according to Newton, and got that one right intuitively.

However, I'm uncertain how to proceed for b and c.

I attempted to setup equations for both bodies.

For body A, I've got:

X component: f - wA(weight of body A) - Tcos(theta) = ma.

Y component: Fn + Tsin(theta) - wA = ma

For body B, I've got:

T - wB = ma

Can I proceed like this or is something off?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: One more tricky 2nd Newtonian Law with friction problem

**Physics Forums | Science Articles, Homework Help, Discussion**