Answer #1
In the laboratory, you are given a metal block, about the size of a brick. You are also given a 2.0-m-long
wooden plank with a pulley attached to one end. Your goal is to determine experimentally the coefficient
of kinetic friction, μ (^) k , between the metal block and the wooden plank.
(a) From the list below, select the additional equipment you will need to do your experiment by
checking the line to the left of each item. Indicate if you intend to use more than one of an item.
(b) Draw a labeled diagram showing how the plank, the metal block, and the additional equipment you
selected will be used to measure μ (^) k.
(c) Briefly outline the procedure you will use, being explicit about what measurements you need to
make and how these measurements will be used to determine μ (^) k.
Use the balance to determine the mass, m , of the metal block. The weight of the block is mg . Attach the
spring scale to the bulldozer; attach the other end of the spring scale to the metal block with string. Allow
the bulldozer to pull the block at constant speed.
The block is in equilibrium. So, the reading of the spring scale while the block is moving is the
friction force on the block; the normal force on the block is equal to its weight. The coefficient of kinetic
friction is equal to the spring scale reading divided by the block’s weight.