Rotations part 1 Flashcards
If an object is in equilibrium the net torque is equal to what?
The net torque is equal to zero in equilibrium
What are the two conditions for an object to be in static equilibrium?
sum of external forces =0
sum of external torques =0
fulcrum
balancing point
Torque
rotational force which causes a change in rotational motion
Torque equation
T = F x r
force must be applied _____ to the radius (lever arm) in order to create rotation
perpendicular
Max rotation
r and F perfectly perpendicular
no rotation when
force is applied straight towards the object
When force is not perpendicular?
T = r Fsinx
T = rFcosx
solve any torque problem with
the sum of external forces equal 0
angular kinematics is measured in?
Radians
angular speed
how fast the angle changes theta/ t
positive angle =
negative angle=
counter clockwise
clockwise
convert linear velocity to angular velocity
v= w x r
w = v/r
convert linear acceleration to angular acceleration
a = A x r
A = a/r
revolutions is…
theta
angular displacement/ 2pi
frequency to angular velocity
2pi(f) rev/sec
2pi(f)/60 rev/min
moment of inertia
an objects resistance to rotational acceleration
rotational inertia is dependent on
- the mass of an object
- the distribution of the mass about the chosen axis of rotation
What objects are easier to accelerate?
objects with a smaller moment of inertia are easier to accelerate
rotational motion
T = I x A
for T = I x A
what happens if F doubles?
I doubles
F doubles, A doubles
I doubles, A(1/2)
sum of forces in x to find Rx
Rx + Fcosx
sum of forces in y to find Ry
Ry- F - F + Fsinx
how to find R (force of an angle without known angle)
Sq/rt (Rx)^2+(Ry)^2
