What I learned
In Unit Two Dynamics, we learned Newton’s Laws. There are
three laws in total. The first law states that an object in motion will stay in
motion and an object at rest will stay at rest unless an outside force is
applied. The second law states that the acceleration of a body is proportional
to the force and inversely proportional to the mass. This concept can also be
represented mathematically as Fnet = ma. The third law states that
for every action force there is an equal and opposite reaction force. We also learned about different kind of forces
for example gravitational force, frictional force and normal force. We use our
understanding of forces and Newton’s Laws to questions that involves finding a
missing force, the mass of an object or acceleration. For this type of
questions we often use the formula F=ma.
We also learned how to solve more complex questions that
involve inclines and more than one objects.
In order to solve this kind of questions, we first have to
draw a labeled free body diagram with arrows. Then, resolve the objects’
gravitational force into its x and y component and use the formula F=ma.
In Unit 3, we learned that when the sum of forces acting on
an object is zero, the object is in equilibrium. There are two different kind
of equilibrium: translational equilibrium and rotational equilibrium. Translational equilibrium occurs when all
objects are at rest (static equilibrium) or moving with a uniform motion in a
straight line (dynamics equilibrium). We use the formula ∑F=0 to solve problems
involving translational equilibrium. We can solve a problem using either
component method or closed vector diagram method.
Component method
Closed vector diagram method
On the other hand,
rotational equilibrium occurs when it is not moving or rotating and the net sum
of torque on the object equals to zero. We use the equation ∑τ=0 and ∑τcw =∑τccw
to solve problems on rotational
equilibrium.
What I found difficult
I found the practices and tests in the Dynamics Unit to be
fairly easy. However, the Equilibrium Unit is a bit harder for me. When I do
questions involving torque, I sometimes get confused about the direction of
torque. I found that the mass attached to a wall by a hinge type of questions
to be most difficult. This is because these questions are more complex and
there are often many forces to consider. Sometimes I am careless or trying to
do the question too fast and I will miss one of the forces and get the answer final
wrong. So I will try to be more careful when I am doing this kind of questions.
My problem solving skills
My strength in problem solving is I found it really easy to
solve questions using the closed vector diagram method. I am also comfortable
using the components method but I found this method involves more work and
takes more time. I am comfortable about calculating angles using sine law of
cosine law. My weakness is that I can get confused when I am finding the
directions of forces. I will try to improve on my weakness by doing more
practices.
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