Construct the free-body diagram for object A and object B in
[link] .
Strategy
We follow the four steps listed in the problem-solving strategy.
Solution
We start by creating a diagram for the first object of interest. In
[link] (a), object A is isolated (circled) and represented by a dot.
(a) The free-body diagram for isolated object A. (b) The free-body diagram for isolated object B. Comparing the two drawings, we see that friction acts in the opposite direction in the two figures. Because object A experiences a force that tends to pull it to the right, friction must act to the left. Because object B experiences a component of its weight that pulls it to the left, down the incline, the friction force must oppose it and act up the ramp. Friction always acts opposite the intended direction of motion.
We now include any force that acts on the body. Here, no applied force is present. The weight of the object acts as a force pointing vertically downward, and the presence of the cord indicates a force of tension pointing away from the object. Object A has one interface and hence experiences a normal force, directed away from the interface. The source of this force is object B, and this normal force is labeled accordingly. Since object B has a tendency to slide down, object A has a tendency to slide up with respect to the interface, so the friction
is directed downward parallel to the inclined plane.
As noted in step 4 of the problem-solving strategy, we then construct the free-body diagram in
[link] (b) using the same approach. Object B experiences two normal forces and two friction forces due to the presence of two contact surfaces. The interface with the inclined plane exerts external forces of
and
, and the interface with object B exerts the normal force
and friction
;
is directed away from object B, and
is opposing the tendency of the relative motion of object B with respect to object A.
Significance
The object under consideration in each part of this problem was circled in gray. When you are first learning how to draw free-body diagrams, you will find it helpful to circle the object before deciding what forces are acting on that particular object. This focuses your attention, preventing you from considering forces that are not acting on the body.
Two blocks in contact
A force is applied to two blocks in contact, as shown.
Strategy
Draw a free-body diagram for each block. Be sure to consider Newton’s third law at the interface where the two blocks touch.
Solution
Significance
is the action force of block 2 on block 1.
is the reaction force of block 1 on block 2. We use these free-body diagrams in
Applications of Newton’s Laws .
A block rests on the table, as shown. A light rope is attached to it and runs over a pulley. The other end of the rope is attached to a second block. The two blocks are said to be coupled. Block
exerts a force due to its weight, which causes the system (two blocks and a string) to accelerate.
Strategy
We assume that the string has no mass so that we do not have to consider it as a separate object. Draw a free-body diagram for each block.
Solution
Significance
Each block accelerates (notice the labels shown for
and
); however, assuming the string remains taut, they accelerate at the same rate. Thus, we have
. If we were to continue solving the problem, we could simply call the acceleration
. Also, we use two free-body diagrams because we are usually finding tension
T , which may require us to use a system of two equations in this type of problem. The tension is the same on both
.
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things
A scanning electron microscope (SEM) is ideal for situations requiring high-resolution imaging of surfaces. It is commonly used in materials science, biology, and geology to examine the topography and composition of samples at a nanoscale level. SEM is particularly useful for studying fine details,
