Force Moment Velocity Distance Physics
This Physics chapter is about Force, Moment, Velocity and Distance.
the line of action is
an extended line drawn colinear with the force
the lever arm is the
distance ι between the line of action and axis of rotation, measured on a line that is perpendicular to both
magnitude of torque =
magnitude of force x lever arm
the torque is positive when…
the force tends to produce a counterclockwise rotation about the axis
if a rigid body is in equilibrium, neither…
its linear motion nor its rotational motion changes
a rigid body is in equilibrium if it has
zero translational acceleration and zero angular acceleration
in equilibrium, the sum of externally applied forces is
torque is what causes _____ ______ to change
the choice of axis is completely arbitrary, because if an object is in equilibrium, it is in equilibrium with respect to…
any axis whatsoever
to a large extent, the directions of the forces acting on an object in equilibrium can be deduced using
choosing the direction of an unknown force backward in the free body diagram simply means that
the value determined will be a negative number
center of gravity of a rigid body is the point at which…
the weight can be considered to act when the torque due to the weight is being calculated
when an object has a symmetrical shape and its weight is distributed uniformly, the center of gravity lies
at its geometrical center
the center of gravity plays an important role in determining whether a group of objects remains in
equilibrium as the weight distribution within changes
according to newton’s second law for rotational motion about a fixed axis, the net external torque is directly proportional to
the angular acceleration
moment of inertia of the particle
I = mr²
-the constant of proportionality between the torque and acceleration
moment of inertia (I) of the body:
sum of the individual moments of inertia
moment of inertia of the body equation
I = m₁r₁² + m₂r₂² = ∑mr²
when forces act on a rigid object, they can affect its motion in two ways:
1) produce translational acceleration (ax and ay)
2) produce torques, causing the object to have angular acceleration α
for translational acceleration (ax ay) we use:
for rotational motion of rigid object around fixed axis
the work done W by a constant force that points in the same direction as displacement is
the rotational work done Wr done by a constant torque T in turning an object through an angle θ is
Wr = Tθ
for rotational work (Wr), θ must be expressed in
rotational kinetic energy: KEr of a rigid object rotating with angular speed w about a fixed axis and having a moment of inertia I is:
KEr = 1/2lw²
angular momentum L of a body rotating around a fixed axis is the product of the body’s moment of inertia I and its angular velocity with respect to that axis:
L = lw
w must be in radians
principle of conservation of angular momentum
when the sum of average external torques is zero, final and initial angular momenta are the same
Lf = Lo
Is it possible for two quantities to have the same units but different dimensions?
Is it possible for two quantities to have the different units but the same dimensions?
On a fishing trip, you catch a 2.8 lb bass, a 13.9 lb rock cod, and a 15.33 lb salmon.
How many significant figures are in 0.00000303?
How many significant figures are in 6.201*10^5?
Which of the following quantities have the dimensions
of time? (a) x/v (b) a/v (c) (2x/a)^1/2 (d) v^2/a
The accuracy of an instrument is called what?
Typically resolution is ______ the smallest division on an instrument.
___________ is the total length of travel.
_______ is the change in position.
Average speed =
Average velocity =
What are the three vectors associated with one dimensional movement?
displacement, velocity, acceleration
A vector has what and what?
magnitude and direction
The instantaneous velocity at a point is equal to what?
The slope of the tangent line to the curve at that point
Acceleration is what?
change in velocity/time
When acceleration and velocity are in the same direction an objects speed will
When acceleration and velocity are in opposite directions an objects speed will
When acceleration is perpendicular to velocity an object is
When acceleration is constant velocity can be given by the equation
v = v0+at
When acceleration is constant the average velocity can be found by the equation
When an object is in free fall it is only subject to the influence of