Consider the modified Atwood's machine:
Two masses (cart m_{A}, hanging block m_{B}) are connected by an ideal string passing over an ideal pulley, as shown. Note that an "ideal string" has the same tension force T everywhere along its length, but that force pulls
Let us assume for now that the friction on the horizontal surface is negligible. Can you figure out all the forces acting on the cart? Fill in the table.
force x y ------------------------------- ------------------------------- total
Now, please write out expressions for the forces acting on the weight.
force x y ------------------------------- ------------------------------- total
You should end up with a set of two equations:
You should also end up with two unknown quantities
If you are careful with your signs, you should be able to solve these two equations for the two unknowns. In other words, given the masses of the cart and weight, you should be able to predict their acceleration.
Copyright © Michael Richmond. This work is licensed under a Creative Commons License.